Adds a NoOpComposer

... which is useful for bring-up of Cuttlefish on Gem5
which does not yet have virtio-gpu or a drm node. It
also does not have vsock which prevents the use of
Cuttlefish's "device config" for finding displays. In
that case, just have a default placeholder display that
we can configure later.

Also, clang-format.

Bug: b/226154708
Test: launch Cuttlefish in `noop` mode on Crosvm and
      check that device still reaches BOOT_COMPLETE
Change-Id: I258bf5b80b3f7523ff655aaf8d3e91c9cf76c047
12 files changed