GDScript: Add exclude_addons_exceptions project setting

[dalexeev]

• Closes Project settings: add Debug > GDScript > Warnings parameter to include/exclude specific add-ons godot-proposals#9146.
• Closes Extend `debug/gdscript/warnings/exclude_addons` to allow exclusion of custom paths. godot-proposals#10099.
• Plugin developers have reported problems several times when users disable exclude_addons.
  • GDScript 2.0: Variant type errors #74532 (comment)
• We also have several important warnings that are treated as errors by default (like NATIVE_METHOD_OVERRIDE). The lack of warnings/errors for actively developed addons is confusing.
  • Inconsistent behaviour of overridden Node methods  #92394 (comment)

[Mickeon]

Bit of an iffy spot to use raw file paths to the .cfg file, especially since the addons folder is hardcoded.

I get we are extremely limited when it comes to UI design here, but this kind of setting would make a whole lot more sense if it was available in the Addons tab as a toggle for each addon, instead. Problem is, this is a bit too specific to deserve a special column, and hiding it behind an "Others" secion would make it too obscure.

I think it would feel a whole lot more natural, beneficial, and encompassing to have both an exclusion list (blacklist) and inclusion list (whitelist, or exceptions as by this PR) of folder/file paths where warnings can apply.
By default, the exclusion list should include the addons folder, and the inclusion list should be empty.

[dalexeev]

@Mickeon I thought about both options and initially implemented the Debug column in the Plugins tab. But after some thought, I decided that this was an overcomplication.

You have only two types of code in your project: your own (including some plugins) and third-party. For your own code, you should stick to a consistent style and warning configuration. If you want to suppress some warnings at the individual file level, there is @warning_ignore and #76020, which I hope will eventually be merged.

The option of excluding arbitrary folders or .gitignore-like config would be less efficient. This can be critical since warnings like UNTYPED_DECLARATION are checked quite often.

[HolonProduction]

From a UX perspective, plugins created through the create plugin wizard should be added to this setting automatically, since they are obviously code of the current user.

Also I'd only show the note in the configuration dialog, when the plugin is not on the list, otherwise users might make an unnecessary trip to the settings just to find the plugin already configured.

[dalexeev]

@HolonProduction Thanks for the comment! I thought about this option, but there are a few questions we should discuss first:

1. Is it fine that the addon editor changes the GDScript settings? Or should we implement the method in the GDScript module and call it in the addon editor using conditional compilation?
2. Should we provide a UI for editing GDScript settings in the addon editor for existing plugins or just add the exception when creating a plugin?
3. If the user renames/moves the plugin through the File System dock, should we update the GDScript settings?

[HolonProduction]

1. I think, if it is fine to check the language name against the hardcoded GDScript language name, it should be fine to meddle with the GDScript settings, checking if a hardcoded settings path exists. But maybe someone from the editor team has more insight on the guidelines for interaction with modules.

2. On one hand side I think it wouldn't hurt to have the option in both places, on the other I think it doesn't really fit with the other stuff in this dialog (properties of the plugin vs. properties of the project). Haven't really made my mind up about this 😅

3. That sounds reasonable and should be possible entirely in the gdscript module. But given that the project settings seem to handle moving stuff with settings that are just a single file path, I'd rather consider a change to make the project settings handle lists of file paths as well.