[CodeView] Hook up CodeViewRecordIO to type serialization path.

Previously support had been added for using CodeViewRecordIO
to read (deserialize) CodeView type records.  This patch adds
support for writing those same records.  With this patch,
reading and writing of CodeView type records finally uses a single
codepath.

Differential Revision: https://reviews.llvm.org/D26253

llvm-svn: 286304