Revert "ash: Replace locale.mojom in cpp"

This reverts commit c0ec2297d6b98e30311896d589a564838d53c9a0.

Reason for revert:
In order to revert this CL:
https://chromium-review.googlesource.com/c/chromium/src/+/1641466
that breaks CQ, I have to revert this one. Sorry.

Original change's description:
> ash: Replace locale.mojom in cpp
> 
> - Move struct/enum/interface in locale.mojom to cpp;
> - Current LocaleUpdateController -> LocaleUpdateControllerImpl;
> 
> Bug: 958205
> Change-Id: Ic7745a45cd600f35310d7581771451f89536cc08
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1647136
> Commit-Queue: Xiyuan Xia <xiyuan@chromium.org>
> Reviewed-by: James Cook <jamescook@chromium.org>
> Reviewed-by: Sam McNally <sammc@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#666724}

TBR=jamescook@chromium.org,xiyuan@chromium.org,sammc@chromium.org

Change-Id: I99ab97a914fd2080396ea1510be7963bd45faa8a
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 958205
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1648328
Reviewed-by: Xida Chen <xidachen@chromium.org>
Commit-Queue: Xida Chen <xidachen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#666749}
32 files changed