extensions: Port SharedModuleService to desktop Android

It's currently owned by ExtensionService, which we can't yet use on
desktop Android. Convert it to a ProfileKeyedService so it can be
accessed without using ExtensionService. Callers to
ExtensionService::shared_module_service() will be cleaned up in a
follow-up CL.

Remove ExtensionService dependencies by using ExtensionUpdater
and ExtensionRegistrar directly.

Bug: 409120449
Change-Id: I736f169d768a41fdcebf0438e680ad022e6b8d02
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6440263
Commit-Queue: Devlin Cronin <rdevlin.cronin@chromium.org>
Commit-Queue: James Cook <jamescook@chromium.org>
Reviewed-by: Stefan Kuhne <skuhne@chromium.org>
Auto-Submit: James Cook <jamescook@chromium.org>
Reviewed-by: Devlin Cronin <rdevlin.cronin@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1444380}