Fix add/remove event listeners in core:sys/wasm

There were multiple issues here:

1. listeners stored in the same key overwriting the previous one
2. missing `use_capture` parameter in `remove_event_listener`/`remove_window_event_listener`

The key used to store the listener function in `listenerMap` was a
javascript `Object`, when used as a key it was thus serialized to
the string `"[object Object]"`, meaning all listeners where effectively
set to the same key when calling `add_event_listener`/`add_window_event_listener`.
Later on when calling `remove_event_listener`/`remove_window_event_listener`,
it then tried to remove the incorrect one or none at all if there was a
mix of the same event name registered on an element or the window.

To fix I implemented a function `listener_key` in the javascript code
which will generate a different key based on the event's:
- `id`: dom element's id or 'window' (when event listener added to the
  window)
- `name`: the event name (eg: `click`), each event handler should be
  removed for the event name it was register on.
- `data`: we can register events with different data, each one generate
  a new listener which has to be removed.
- `callback`: same as `data`, if you register two similar handler but
  with two different callback, each one should be removed.
- `useCapture`: this one is a bit tricky, but when you register an event
  handler in javascript, if you don't pass `useCapture`, it defaults to `false`.
  When you remove an handler, you have to pass the exact same
  `useCapture` option you registered it with. In this case, we allowed
  to register an event with different `useCapture`, but didn't allow to
  pass the `useCapture` when removing it. We always called `removeEventListener`
  without the `useCapture` parameter which removed the handler properly
  only when it was registered with `useCapture=false`.

I also switched the `WasmMemoryInterface.listenerMap` from `{}`
(javascript object) to a `new Map()`, which is available everywhere
nowadays.

core/sys/wasm/js/events.odin

@@ -346,13 +346,13 @@ add_event_listener :: proc(id: string, kind: Event_Kind, user_data: rawptr, call
 	return _add_event_listener(id, event_kind_string[kind], kind, user_data, callback, use_capture)
 }
 
-remove_event_listener :: proc(id: string, kind: Event_Kind, user_data: rawptr, callback: proc(e: Event)) -> bool {
+remove_event_listener :: proc(id: string, kind: Event_Kind, user_data: rawptr, callback: proc(e: Event), use_capture := false) -> bool {
 	@(default_calling_convention="contextless")
 	foreign dom_lib {
 		@(link_name="remove_event_listener")
-		_remove_event_listener :: proc(id: string, name: string, user_data: rawptr, callback: proc "odin" (Event)) -> bool ---
+		_remove_event_listener :: proc(id: string, name: string, user_data: rawptr, callback: proc "odin" (Event), use_capture: bool) -> bool ---
 	}
-	return _remove_event_listener(id, event_kind_string[kind], user_data, callback)
+	return _remove_event_listener(id, event_kind_string[kind], user_data, callback, use_capture)
 }
 
 add_window_event_listener :: proc(kind: Event_Kind, user_data: rawptr, callback: proc(e: Event), use_capture := false) -> bool {
@@ -364,20 +364,26 @@ add_window_event_listener :: proc(kind: Event_Kind, user_data: rawptr, callback:
 	return _add_window_event_listener(event_kind_string[kind], kind, user_data, callback, use_capture)
 }
 
-remove_window_event_listener :: proc(kind: Event_Kind, user_data: rawptr, callback: proc(e: Event)) -> bool {
+remove_window_event_listener :: proc(kind: Event_Kind, user_data: rawptr, callback: proc(e: Event), use_capture := false) -> bool {
 	@(default_calling_convention="contextless")
 	foreign dom_lib {
 		@(link_name="remove_window_event_listener")
-		_remove_window_event_listener :: proc(name: string, user_data: rawptr, callback: proc "odin" (Event)) -> bool ---
+		_remove_window_event_listener :: proc(name: string, user_data: rawptr, callback: proc "odin" (Event), use_capture: bool) -> bool ---
 	}
-	return _remove_window_event_listener(event_kind_string[kind], user_data, callback)
+	return _remove_window_event_listener(event_kind_string[kind], user_data, callback, use_capture)
 }
 
 remove_event_listener_from_event :: proc(e: Event) -> bool {
+  from_use_capture_false: bool
+  from_use_capture_true: bool
 	if e.id == "" {
-		return remove_window_event_listener(e.kind, e.user_data, e.callback)
-	}
-	return remove_event_listener(e.id, e.kind, e.user_data, e.callback)
+    from_use_capture_false = remove_window_event_listener(e.kind, e.user_data, e.callback, false)
+    from_use_capture_true = remove_window_event_listener(e.kind, e.user_data, e.callback, true)
+	} else {
+    from_use_capture_false = remove_event_listener(e.id, e.kind, e.user_data, e.callback, false)
+    from_use_capture_true = remove_event_listener(e.id, e.kind, e.user_data, e.callback, true)
+  }
+  return from_use_capture_false || from_use_capture_true
 }
 
 add_custom_event_listener :: proc(id: string, name: string, user_data: rawptr, callback: proc(e: Event), use_capture := false) -> bool {
@@ -388,13 +394,13 @@ add_custom_event_listener :: proc(id: string, name: string, user_data: rawptr, c
 	}
 	return _add_event_listener(id, name, .Custom, user_data, callback, use_capture)
 }
-remove_custom_event_listener :: proc(id: string, name: string, user_data: rawptr, callback: proc(e: Event)) -> bool {
+remove_custom_event_listener :: proc(id: string, name: string, user_data: rawptr, callback: proc(e: Event), use_capture := false) -> bool {
 	@(default_calling_convention="contextless")
 	foreign dom_lib {
 		@(link_name="remove_event_listener")
-		_remove_event_listener :: proc(id: string, name: string, user_data: rawptr, callback: proc "odin" (Event)) -> bool ---
+		_remove_event_listener :: proc(id: string, name: string, user_data: rawptr, callback: proc "odin" (Event), use_capture: bool) -> bool ---
 	}
-	return _remove_event_listener(id, name, user_data, callback)
+	return _remove_event_listener(id, name, user_data, callback, use_capture)
 }
 
 get_gamepad_state :: proc "contextless" (index: int, s: ^Gamepad_State) -> bool {