[ffx] Port `ffx log` and `ffx component run` to FDomain

A weird interdependency between these two plugins means they both have
to go at once.

Change-Id: I6a6a6964a003c468242e5ba6f7cf6506b92aaf3c
Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1483977
Reviewed-by: Brian Bosak <bbosak@google.com>
Fuchsia-Auto-Submit: Casey Dahlin <sadmac@google.com>
Commit-Queue: Casey Dahlin <sadmac@google.com>