Properly remember snapping options per-project

[KoBeWi]

This PR makes snapping options properly remembered and re-used. No more resetting the grid to 8x8 for no reason, the editor will remember the settings you set last time and use it for each new scene (both for 2D and 3D.
TextureRegionEditor will also remember its snapping settings.

Closes godotengine/godot-proposals#1348 and closes godotengine/godot-proposals#4362 (if these options are remembered properly within the project then a setting isn't really necessary anymore, but idk)

Edit by Akien: Confirmed this is a sufficient fix for those proposals, so changed to closing keywords.

[oxeron]

Will this feature be back ported to 3.5 branch ?

[akien-mga]

Thanks!

[YuriSizov]

Cherry-picked for 4.0.3.

[YuriSizov]

Will this feature be back ported to 3.5 branch ?

If someone implements it :) It should be doable.

[capnm]

@YuriSizov I don't see why (please double check) but this commit causes looping in

godot/editor/plugins/canvas_item_editor_plugin.cpp

Lines 2784 to 2786 in c151d32

	while ((transform * ruler_transform).get_scale().x < 50 || (transform * ruler_transform).get_scale().y < 50) {
	ruler_transform.scale_basis(Point2(2, 2));
	}

See #75749
Reverting it fixed for me the issue at current tip.

[YuriSizov]

Thanks for looking into it, let's keep the discussion to one place and continue it in your bug report.