Rewrite the service management to leverage Docker Compose

[lucatume]

This updates the code to leverage Docker Compose own system of dependency management and IP address resolution.
This results in a less clunky experience, more robust handling of dependencies, speed improvment and less code.

I've added healthcheck entries to the base containers to deleagate the complexity of managing their state to Docker Compose.
Depending containers, e.g. the wordpress or the slic one, can now depend on healthy services.
Along with this the requirements of the PHP CLI to have the mysql extension installed is gone.

I've also leveraged the network.aliases configuration to make sure the wordpress service IP is resolved at the network level, avoiding the fetching and setting of IP addresses in the PHP code.

Since I have added it for debugging purposes, I've refined and added the dc command to run direct Docker Compose commands in the stack.

Finally, I've introduced a slic_cache_ API to cache values across the application. Right now a simple array, I'm working on a Redis based solution next (since we have the redis service).

Screencast

[lucatume]

I've been using this for my day-to-day work on slic for a week and I do not seem to have broken anything. I will spin up a TEC build using this branch to test it out in CI context.

[lucatume]

Tested with an ECP build -- I've used the containers from version 1.2.2 (they did not change) and it works.

[borkweb]

The first time I tried to look at this, I failed to get the containers to fetch (and I tried a bunch of things). I just tried again and it worked like a champ. I'm able to cleanly run tests 🌵 💨

Some tests are failing in weird ways.

[borkweb]

Actually, I'm getting some unexpected errors while running slic run wpunit on the-events-calendar, so I'm unsure what the deal is.

[lucatume]

Actually, I'm getting some unexpected errors while running slic run wpunit on the-events-calendar, so I'm unsure what the deal is.

Could you run slic down && slic reset wp && slic up and let me know what the issue is?

[borkweb]

Perhaps the slic reset wp was the key. Runs like a champ, now! Nice and speedy.