Canonicalize file path for insertion by legacy apps

Apps with legacy external storage can try to create entries in MP for
file paths in other apps external private directories by using a
non-canonical path in insertion calls.

Test: atest LegacyStorageHostTest#testInsertToOtherAppPrivateDirFails
Bug: 276898626
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:3c0f583f5dc3f4d395fa2423ab72dbd902c0c6c8)
Merged-In: If4c941c8156f19459b3ec6cbaf705824ecc2ba77
Change-Id: If4c941c8156f19459b3ec6cbaf705824ecc2ba77
1 file changed