Remove member signature and inner classes from signature-patterns.csv

Previously, the signature-patterns.csv file included a lot of
implementation details, e.g. the signatures of dex members or inner
classes that are not part of any API, including the hidden API.

This change will remove all member signatures and inner class names
from the file and replace them with just the outermost qualified class
name.

That will still leave some implementation details, e.g. the names of
implementation only classes and packages.

Bug: 194063708
Test: atest --host verify_overlaps_test signature_patterns_test
      m out/soong/hiddenapi/hiddenapi-flags.csv
      - manually change files to cause difference in flags to check
        that it detects the differences.
Change-Id: I9de6a2a6129e875e19f7ded5fae578cbdb584660