fdsan: make the tag type values sequential.

In retrospect, allocating tag types from both ends will just make the
future creation of user-defined tags harder, because constants that are
introduced, and then used in previous versions might collide with
user-defined tags. Move all of the tag values to the front, so that we
can allocate from the end to minimize this.

Test: bionic_unit_tests
Change-Id: I5063adf8301b1063bd4931a6ce8b70dfe2411efd