Docker Compose + GitHub Actions + Layers Cache

Decrease build time of docker compose inside GitHub Actions using layers cache.

2x faster builds:

Description

.github/workflows/not-cached.yml uses ./docker-compose.ci.not-cached.yml. Push to ghcr.io using the :not-cached tag to avoid collisions
.github/workflows/cached.yml uses ./docker-compose.yml. Caching achieved by:
- ENV variables DOCKER_BUILDKIT and COMPOSE_DOCKER_CLI_BUILD
- docker/setup-buildx-action
- --build-arg BUILDKIT_INLINE_CACHE=1
- cache_from inside docker-compose file:
```
build:
  context: ./app1
  cache_from:
  - ghcr.io/cyanofresh/docker-compose-ga-cache-example_app1
```