Allow granting URI permissions to com.android.settings.module_licenses.

Exempts this new ContentProvider for providing mainline module licenses.

Also sets ApplicationInfo.publicSourceDir for APEXes.

Bug: 135183006
Test: open module licenses, click app, verify file opens
Change-Id: Iec4f1de198525f7cd176a52d8448a2c71b6aabc0