The classes ProgramInfo and ShaderInfo are being moved into
ProgramExecutableVk along with the ProgramVk members mDefaultProgramInfo
and mLineRasterProgramInfo.   This refactor is necessary since these
members are common between ProgramVks and ProgramPipelineVks.

Bug: angleproject:3570
Change-Id: I94cdb1096c6a0c007d858135af694da58d7897ff
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2068901
Commit-Queue: Tim Van Patten <timvp@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>