Array of files is saved as uids in ProjectSettings since 4.4

[IceflowRE]

Tested versions

• v4.4.stable.official [4c311cb]
• v4.5.dev1.official [97241ff]

System information

Godot v4.4.stable - Windows 11 (build 26100) - Multi-window, 2 monitors - Vulkan (Forward+) - dedicated NVIDIA GeForce GTX 1080 Ti (NVIDIA; 32.0.15.7216) - AMD Ryzen 9 7900X 12-Core Processor (24 threads)

Issue description

When adding a property to the ProjectSettings with TYPE_ARRAY, PROPERTY_HINT_ARRAY_TYPE and TYPE_STRING, PROPERTY_HINT_FILE, up to 4.4 the content was an array of elements using res://, since 4.4. this is an array of uids.

Why is this a bad breaking?

1. Inconsistency: A single TYPE_STRING with PROPERTY_HINT_FILE is still saved using the path.
2. The project settings are not upgraded by the Upgrade to UID routine. Means especially plugins have to consider both variants actively.
3. There is no fallback anymore to the path variant, if the UID gets deleted, missing it is not possible to access the file anymore, or even know which file it was.
4. If the UID changes the project setting is not automatically updated.

Steps to reproduce

Select files in ProjectSettings > General > Plugins > Testing.
The files are saved as uids in the project.godot.

Minimal reproduction project (MRP)

new_game_project.zip

[dalexeev]

• See @export_file need to allow you to keep the old behavior of setting it as res path instead of uid if desired (breaking change!) #104379.