Update prefect server start command to specify and disable port mappings

[joshmeek]

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• adds new tests (if appropriate)
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What does this PR change?

Open PR up for discussion if this is how we want optional port allocations to work when running prefect server start. This allows ports from the server services to be binded to different ports on the host machine. For this to work I had to add __HOST_PORT options to some of the services in config.toml. I'm guessing this is due to some hardcoded ports that these services use inside their containers. (e.g. overwriting config.server.hasura.port broke communication inside the containers when they ran)

This implementation allows us to set ports through CLI --postgres-port or environment variables PREFECT__SERVER__DATABASE__HOST_PORT however we can definitely go a different route.

This PR also adds the options to disable port mappings on a per-service basis. (e.g. --no-postgres-port)

Closes #2225

Why is this PR important?

Port customization for the start command is a nice convenience to have.

[codecov]

Codecov Report

Merging #2228 into master will increase coverage by 0.32%.
The diff coverage is 100.00%.

[cicdw]

I think this makes sense

[cicdw]

👍 only thing I wonder is whether anything wonky could happen when serving a docker setup from a temporary docker compose script location (e.g., if someone leaves the server running for a long time and the temporary docker compose file gets cleaned up by the system, does that matter?)

[joshmeek]

@cicdw I just tested it by spinning it up using the no-port options which creates a tempdir to house the docker compose file. Then while it was running I manually went to the tempdir and deleted the file. Everything continued to run and when I shut it down it all shut down properly 👍