Lacros: Implement AccountManagerFacade::CreateAccessTokenFetcher

Bug: 1167183
Test: components_unittests
Change-Id: I6fb707e1b6e32e1ecf25257c7851f1a43e34ed65
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2752885


Commit-Queue: Kush Sinha <sinhak@chromium.org>
Reviewed-by: Boris Sazonov <bsazonov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#864684}