Reland "Move gn setup for vulkan library/headers into their own third_party directory."

This reverts commit 2c2a119f945eedaced4bf081347a53f05cf0c39c.

Reason for revert: Relanding with fixes

Original change's description:
> Revert "Move gn setup for vulkan library/headers into their own third_party directory."
> 
> This reverts commit 477094250cd55a38d4d796ab6c50eb57bdba65e1.
> 
> Reason for revert:
> I think we know this broke the MoltenVK bots.  It also appears to have broken the Fuchsia roll: https://logs.chromium.org/v/?s=fuchsia%2Fbuildbucket%2Fcr-buildbucket.appspot.com%2F8945885190914943680%2F%2B%2Fsteps%2Fbuild%2F0%2Fsteps%2Fbuild_fuchsia%2F0%2Fsteps%2Fgn_gen%2F0%2Fstdout
> 
> Original change's description:
> > Move gn setup for vulkan library/headers into their own third_party directory.
> > 
> > Bug: skia:
> > Change-Id: I4605f0d962271efb77bf3c17f1b0daaaddfb51c8
> > Reviewed-on: https://skia-review.googlesource.com/128540
> > Commit-Queue: Greg Daniel <egdaniel@google.com>
> > Reviewed-by: Mike Klein <mtklein@google.com>
> > Reviewed-by: Ben Wagner <bungeman@google.com>
> 
> TBR=egdaniel@google.com,mtklein@google.com,bungeman@google.com
> 
> Change-Id: I6e41d98e39883eff34424a2f352b0c8adec178db
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Bug: skia:
> Reviewed-on: https://skia-review.googlesource.com/129444
> Reviewed-by: Mike Klein <mtklein@google.com>
> Commit-Queue: Mike Klein <mtklein@google.com>

Bug: skia:
Change-Id: I26b4b1f7196dd1bd8bf2e7641ef741c90c742c81
Reviewed-on: https://skia-review.googlesource.com/129445
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>

0 files changed, 0 insertions, 0 deletions