Resubmit "[CodeView] Provide a common interface for type collections."

This was originally reverted because it was a breaking a bunch
of bots and the breakage was not surfacing on Windows.  After much
head-scratching this was ultimately traced back to a bug in the
lit test runner related to its pipe handling.  Now that the bug
in lit is fixed, Windows correctly reports these test failures,
and as such I have finally (hopefully) fixed all of them in this
patch.

llvm-svn: 303446