investigate cache invalidation of preloaded scripts with CACHE_MODE_REPLACE_DEEP since 4.3

[Qubus0]

@ZackeryRSmith found out scripts from preloaded scenes can be modded when loading with the new CACHE_MODE_REPLACE_DEEP added to 4.3 in godotengine#88664

ResourceLoader.load("scene path here", "", ResourceLoader.CACHE_MODE_REPLACE_DEEP)

ref discord message

we'll have to check if we can

• do this with every preloaded scene to refresh scripts (preload("...tscn") containing a script)
• do this with directly preloaded scripts preload("...gd")
• if not, if we can add a script to a scene as subresource and then load it to refresh the script too

[ZackeryRSmith]

Here's my go at a simple, minimal reproduction project, with extra logging! It seems like

1. You can do this to refresh any non-preloaded scripts in a preloaded scene
2. You cannot do this directly with preloaded scripts
3. You cannot do this with indirectly preloaded scripts, e.g., adding the script as a subsource or as a separate dummy scene with the preloaded script attached

This method doesn't apply to preloaded scripts at all, based on my testing. However, it does get around scripts inside of preloaded scenes, which is most commonly the case. In my MRP, it's also possible to use the regular CACHE_MODE_REPLACE, but this may be due to the simplicity of the example. Regardless, here it is

tested on Godot 4.3 stable
mrp.zip

mrp_vid.mp4