Add ability to set default 2D ruler state

[timothyqiu]

Closes godotengine/godot-proposals#8795

[KoBeWi]

As I said already in the proposal, adding an editor setting for something you can toggle once per project is rather meh. Especially when we don't really have other setting like that in the 2D section - everything is stored in editor layout (just like the rulers).

[timothyqiu]

Ruler state is still stored per scene. This editor setting determines the default value for ruler state.

Ruler state is currently not once per project. Whether to show the ruler in a new scene depends on whether the last scene's ruler is shown.

we don't really have other setting like that in the 2D section

I can make default value for other settings also configurable if you want.

[KoBeWi]

Ruler state is currently not once per project.

Check #74682
We could do the same for rulers.

[timothyqiu]

Check #74682
We could do the same for rulers.

The original proposal want to be able to set "Editor Default", and this is about implementing an auto-remembering "Project Default".

These two features operate at different levels. They can co-exist.

For an auto-remembering project default. Users still have the problem of not being able to disable auto-remembering. That does not solve the problem of the original proposal. Turning on rulers occasionally for one scene breaks the default.

I understand to urge to make the editor feel "smart". However, this should be based on providing full functionality and we should not make choices for the user.