Add tests for ACTION_OPEN_DOCUMENT_TREE

Verify that restricted directories such as Android/data and Android/obb
are not accessed despite use of ZWS characters.

Test: atest MediaStoreUiTest
Bug: 341680936
Flag: EXEMPT bug fix
Change-Id: I6ce0b5954cf8b9c8243bd012ee8fc6b24e174058
Merged-In: I6ce0b5954cf8b9c8243bd012ee8fc6b24e174058