fuchsia: Replace FIDL C++ bindings with LLCPP.

Previously goldfish ICD uses FIDL C++ bindings which
has dependency on the default async dispatcher and
caused some binary dependency issues. This change
migrates all usages of C++ bindings to LLCPP to
eliminate that dependency.

Bug: fxbug.dev/56565
Bug: fxbug.dev/55650

TEST=gfx_unittests, escher_tests on Fuchsia

Change-Id: I0815e210b1630ce2ea9fd32222ddb4a32bbf8644
7 files changed