Move filesystem and leveldb services off SM

Moves the test-only filesystem and leveldb services off of Service
Manager APIs. These "services" directories both contain implementation
details used by other parts of the system (so they aren't dead code),
but their test coverage has been implemented using Service Manager
infrastructure, including (unnecessarily) out-of-process service
executables.

This simplifies all of that by dropping Service Manager dependencies
in favor of direct mojom interface usage.

Bug: 977637
Change-Id: Id9ba6b88457e943d582b9de589bd120caf3413de
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1725052
Reviewed-by: Marijn Kruisselbrink <mek@chromium.org>
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Commit-Queue: Ken Rockot <rockot@google.com>
Cr-Commit-Position: refs/heads/master@{#682030}
32 files changed