Switch Qt demo apps to gRPC launcher API

Switch Qt demo apps to gRPC launcher API

Changes:
- Update SRCREV in libqtappfw, launcher, and homescreen recipes to
  pick up gRPC API changes.
- Update libqtappfw recipe for switch to meson instead of CMake, and
  add new protobuf and gRPC dependencies.
- Update launcher recipe to pull in new libqtappfw dependency, and
  update some formatting for consistency with the other recipes.

Bug-AGL: SPEC-4559

Signed-off-by: Scott Murray <scott.murray@konsulko.com>
Change-Id: I6ec0f53a0cc68bcf9b434086d99e8849c11198f3