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.