Add `restart` and `stop` options to `dolt sql-server`

[timsehn]

A customer asked for options to stop and restart a running dolt-sql-server. The idea is to implement dolt sql-server --restart and dolt sql-server --stop. If there are multiple running servers ion the machine, the correct process would be identified by the options like port and data directory.

This is extra useful because there is no way to "restart" a dolt sql-server right now. SIGHUP just quits.