Add an import setting use_legacy_names for 3.3 compatibility.

[lyuma]

During the development of 3.3, internationalization features were added to allow arbitrary bone and node names.
However, doing so will break all references and existing animation clips for projects upgraded from 3.2
This adds an import setting, enabled by default, but disabled for newly generated .import files which restores the old behavior.

This addresses issue #47977.

PR #47742 was recently merged, but is insufficient to cover the whole issue. I made that PR part of the use_legacy_names import setting introduced in this change.

This commit effectively reverts the three commits f1e8ec9 and b032067 and 1f87bca behind the use_legacy_names import setting.

CC @fire @akien-mga

A new fairly comprehensive test project generated from 3.2.3 is here:
BoneSanitizationFixed.zip

based on the following model:
https://github.com/godotengine/godot-tests/blob/master/tests/blend_export/gltf/45545-relax-name-sanitization.gltf
Includes scene node references, cross-scene animation references and other fun cases.

Old version of test project is here: BoneSanitization.zip Apparently some changes were made in October so this project has bone names with "." in them which was not allowed in 3.2.3

[lyuma]

Note that this change does not affect DAE or OBJ formats.

I am pretty sure that the only place those files can be affected by this change is the call to node->set_name() as that is where the excess validation was formerly done:

editor/import/resource_impoter_obj.cpp line 440:

mi->set_name(E->get()->get_name());

and editor/import/editor_import_collada.cpp line 333:

node->set_name(p_node->name);

Sanitization might be needed there if compatibility is desired for obj scenes or collada.
It's hard for me to evaluate if it's good or bad to make these changes, and I don't have any good test models to use.

[akien-mga]

This part is missing from the legacy branch. Though I guess this might be on purpose, to keep the same behavior as before (i.e. potentially an empty bone name?).

[akien-mga]

Thanks!