[DocsUI, Search]: Surface query exceptions.

Some exceptions that occur when querying a content provider client
contain information interesting to the user. This CL stops catching
exceptions at the base class. Instead it let extending classes to catch
them and pass them to the caller via exception field of the
DirectoryResult object.

Bug: 427555916
Test: atest DocumentsUIGoogleTests
Flag: com.android.documentsui.flags.use_search_v2_read_only
Change-Id: I5aee689a9c970c990ae22ca719034afbb317618e