WIP:MacOS shared folder config + cached option

[iberdinsky-skilld]

Two things done here:

1. Changed shared folder location. Now it is env variable.
2. Added macOS composer override file. To use cached option in volumes: https://docs.docker.com/docker-for-mac/osxfs-caching/

[koskinpark]

here better to add then override for ports of mailhog too.
ports: - "8025:8025"

[iberdinsky-skilld]

https://github.com/skilld-labs/skilld-docker-container/pull/38/files#diff-1c5b1e66e569d11705ad352d61a06a7cR39

[andypost]

yep Macos needs portmapping, better to add it here

[andypost]

I found only 2 issues: naming of mysql var & expose port for mailhog

[andypost]

please give it better name a-la MYSQL_DATA_DIR

[andypost]

yep Macos needs portmapping, better to add it here

[gumanista]

In .env file we have
COMPOSE_FILE=./docker/docker-compose.yml:./docker/docker-compose.override.yml
This may be used to add mac-specific config. So it can be docker-compose.mac.yml and link it as:
COMPOSE_FILE=./docker/docker-compose.yml:.docker/docker-compose.mac.yml:./docker/docker-compose.override.yml

also we have OS-detection and it can be used to handle os-specific tasks