InputEventKey matching logic described in the docs does not match implementation

**Your Godot version: 4.5.1, 4.3, probably relevant for most 4.X versions**

**Issue description:**

`InputEventKey` documentation states the following:
> When events are compared, properties are checked in the following priority - `keycode`, `physical_keycode` and `unicode`. Events with the first matching value will be considered equal.

To me this sounds like all three fields are compared and if any of them are equal then the events are considered equal. However, in practice the behavior is different: `keycode`, `physical_keycode` and `key_label` (not `unicode`!) are checked on the first event, and the first field that is set is used for comparison. If that field has the same value on the other event then it is considered as matching the first event. (Note that this logic is not symmetric. Swapping the events could change the result if the events have a different fields set.)

Relevant code: https://github.com/godotengine/godot/blob/master/core/input/input_event.cpp#L608-L629

**URL to the documentation page:**

https://docs.godotengine.org/en/stable/classes/class_inputeventkey.html