[Fuchsia] FakeComponentContext to be able to help test against Agents from unittests

Test: Starting/connecting in temp unit test locally to make sure things don't blow up.
Bug: None
Change-Id: If28ad799f228d2490d584b303c79d080ec36e6b3
Reviewed-on: https://chromium-review.googlesource.com/c/1464042
Commit-Queue: Wez <wez@chromium.org>
Reviewed-by: Wez <wez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#631874}
3 files changed