Singleton that manages [InputEventAction].
Manages all [InputEventAction] which can be created/modified from the project settings menu [b]Project > Project Settings > Input Map[/b] or in code with [method add_action] and [method action_add_event]. See [method Node._input].
$DOCS_URL/tutorials/inputs/inputevent.html#inputmap
Returns an array of all actions in the [InputMap].
Clears all [InputEventAction] in the [InputMap] and load it anew from [ProjectSettings].