This is the initial CL to start migrating to abseil in various places:
- formatutils.h
- FramebufferVk.h
- Program.h
- ProgramExecutableVk.h
- RewriteRowMajorMatrices.cpp

This intentionally hits a couple different places in the code to make
sure the abseil dependencies are added to the required targets.

Bug: angleproject:4873
Change-Id: I68c7d067b6912b0cc0ecde231501dbed92f0b189
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2321735
Commit-Queue: Tim Van Patten <timvp@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Charlie Lao <cclao@google.com>