[Fuchsia] Remove ComponentContext and generic zx::channel-based APIs.

Bug: 920920
Change-Id: I42a128e6bc41bfd57b42e0f08524bf817e5f3914
Reviewed-on: https://chromium-review.googlesource.com/c/1455764
Commit-Queue: Wez <wez@chromium.org>
Reviewed-by: Sergey Ulanov <sergeyu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#631383}
10 files changed