Fix get_rpc_config() missing return configurations

[dragonhunt02]

Fixes bug #105675 (comment) introduced by #96024

GDScript RPC configurations (set by @rpc annotations) are now returned by get_rpc_config() call.

Internal interface is kept stable by adding an optional parameter defaulting to false.
Exposed GDScript get_rpc_config() defaults to true, so default behaviour is changed to return attached GDScript configs too.

[dragonhunt02]

Commits are squashed now

[Faless]

Internal interface is kept stable by adding an optional parameter defaulting to false.

Adding a default parameter breaks the API for extensions (as reported by the check), so this would need a compatibility method.

I'm not sure I fully understand the issue, it appears that #96024 was changed after the initial review, and changed both the const-ness and the name, resulting in a somewhat more confusing API.

We should re-evaluate the original change and see what we can do about that.

[dragonhunt02]

@Faless Thanks for your review. I read your new PR and the purpose of Node::get_node_rpc_config seems clear now in documentation.

From a Node, this gets functions with @rpc annotation

get_script().get_rpc_config()

this gets RPCs set with rpc_config()

get_node_rpc_config()

I think a utility method to get available rpcs of both Node and its Script could be useful still.
I may consider opening a different PR as enhancement in future.

Thank you again.