[lit] Rename lit.{TestFormats,Util} to their aliased names {formats,util}.

 - With compatibility hack in lit.__init__, so this hopefully shouldn't break
   anything.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188040 91177308-0d34-0410-b5e6-96231b3b80d8
7 files changed