Object.get_meta & has_meta doc mentions is_valid_identifier but deprecated (prefer is_valid_ascii_identifier)

[hsandt]

Your Godot version:

4.6

Issue description:

The doc for Object.get_meta and has_meta says:

Note: A metadata's name must be a valid identifier as per StringName.is_valid_identifier() method.

But clicking on the hyperlinks shows that is_valid_identifier is deprecated:

Deprecated: Use is_valid_ascii_identifier() instead.

So we might as well just mention is_valid_ascii_identifier() from the start.

URL to the documentation page:

https://docs.godotengine.org/en/4.6/classes/class_object.html#class-object-method-get-meta
https://docs.godotengine.org/en/4.6/classes/class_object.html#class-object-method-has-meta