Add GLOBAL_DEF_INTERNAL to hide specific settings

[KoBeWi]

I discovered this line:

godot/core/config/project_settings.cpp

Line 347 in 4d2ecde

if (vc.name.begins_with("input/") || vc.name.begins_with("import/") || vc.name.begins_with("export/") || vc.name.begins_with("/remap") || vc.name.begins_with("/locale") || vc.name.begins_with("/autoload")) {

which is probably the best way to filter out properties from Project Settings. For unknown reason though, it was checking /something instead of something/ for some settings (which also caused autoloads to not be hidden previously, which was then patched somewhere else). There was also export/ filter, which was probably unused since export_presets.cfg was added. And then there is remap/ and locale/ filter. It wasn't working, but seems like locale group has some settings that should be visible, so I removed this and only hidden 2 settings from that group (but maybe there is more settings that could be hidden).

Resolves #58456
Alternative to #61450

[KoBeWi]

Pushed some changes. I made the built-in input actions into internal properties and added docs for the internal properties added in this PR (it's ok to document them I think).

As for the group filter line, it has to stay, because it handles dynamically created properties. I modified it further as import/ isn't actually used - changed it to importer_defaults/.

I noticed there is some code that checks whether "internationalization/locale/translation_remaps" (and other settings) exists. The check might be not necessary anymore (and hopefully it won't break .-. )

[akien-mga]

Seems fine for the time being, though in discussion @YuriSizov and I agreed that it feels like we could go further in dehardcoding the prefixes in _get_property_list.

One option could be to add something like ProjectSettings::get_singleton()->set_prefix_to_hide(String path, bool hide) so that the code that adds such settings can be responsible for hiding them too (which makes it available to plugins).

[akien-mga]

Thanks!