Fix localized files leaking into synced folder targets

[AlexNsbmr]

Problem

When a target uses a synced folder and that folder contains localized resources (*.lproj/Foo.strings), the localized files become members of every target syncing the folder, even when a target excludes them via includes:/excludes:.

XcodeGen does write the excluded localized files into the target's PBXFileSystemSynchronizedBuildFileExceptionSet.membershipExceptions, but Xcode ignores them, because they use the per-language path form:

Resources/en.lproj/AppShortcuts.strings

Xcode only honors localized exclusions in the variant-group form (the same thing Xcode writes when you uncheck a localized file's target membership in the File inspector):

/Localized: Resources/AppShortcuts.strings

In practice this leaks e.g. AppShortcuts.strings into app extensions / UI-test targets that have no AppShortcutsProvider, producing build warnings like "This phrase is not used in any App Shortcut or as a Negative Phrase" and "Unable to read App Intents metadata, AppShortcuts phrases will go through basic validation".

Fix

In PBXProjGenerator.configureMembershipExceptions, rewrite exception paths for files inside a *.lproj directory to the /Localized: variant-group form (with the .lproj component removed). The surrounding Set dedupes the per-language entries into one.

Verified

• New unit test passes.
• Confirmed on a real multi-target project (app + widget + notification-service + UI-tests): with the fix, the localized app-only strings are excluded from the secondary targets, the app itself keeps them, and the App Intents build warnings are gone with no project.yml change.

[AlexNsbmr]

@yonaskolb could you take a look on my PR when you have some time? Thanks

[yonaskolb]

Thanks @AlexNsbmr.

/Localized: <path without the .lproj folder> matches what Xcode writes for localized files in synced folders (e.g. "/Localized: Resources/Localizable.strings", "/Localized: MainInterface.storyboard" in Xcode-generated projects), so the core fix is correct.

Issue: language-specific selections become all-language exclusions

Xcode sets synced-folder target membership per localized file, not per language, but the generated exceptions come from concrete per-language paths. Rewriting every .lproj path drops the language, so specs that select only some languages now exclude all of them. Output generated from this branch:

Spec	Generated membershipExceptions	Result
excludes: ["Resources/Base.lproj/Main.storyboard"]	/Localized: Resources/Main.storyboard	✅
excludes: ["en.lproj/Root.strings"] (.lproj at the synced root)	/Localized: Root.strings	✅
excludes: ["Resources/fr.lproj"]	/Localized: Resources/AppShortcuts.strings, /Localized: Resources/Localizable.strings	⚠️ excluded in every language
excludes: ["Resources/fr.lproj/Localizable.strings"]	/Localized: Resources/Localizable.strings	⚠️ excluded in every language
includes: ["a.swift", "Resources/en.lproj/*"]	/Localized: entries for both files	❌ explicitly included English files are excluded too

The last case is the most serious. Previously the target received extra languages; with this change it silently loses strings that were explicitly included.

Suggested approach

1. Only write /Localized: X when every language copy of X on disk is excluded (e.g. group exception paths by path-without-.lproj and compare against the .lproj copies that exist).
2. When only some languages are excluded, keep the per-language paths rather than widening the exclusion, and log a warning that Xcode can't exclude individual languages from a synced folder. Throwing an error would break specs that generate successfully today.
3. Check how Base.lproj storyboards/xibs pair with their per-language .strings companions (e.g. Base.lproj/Main.storyboard + fr.lproj/Main.strings). The file extensions differ but Xcode treats them as the same localized item, so grouping by exact filename may not be enough.

Tests
Add cases for: excluding a whole language folder, excluding one language's file, includes that pick only some languages, .lproj at the synced root, nested paths, .stringsdict, a Base.lproj storyboard with .strings companions, and a synced Info.plist exception alongside localized ones.