Automatically sync the configuration on server startup

[sandhose]

This does two things:

• automatically sync the configuration when starting the server (unless the --no-sync option is used)
• automatically run migrations before running mas-cli config sync

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[AndrewFerr]

Thanks for this! I tested it locally and it works for me.

I have only a minor change request to the docs. (The Rust code is beyond my expertise at the moment.)