Description:
This PR is a collection of small fixes that are not SWO-specific.

Which issue(s) this PR fixes:

• wait for postgres to finish starting after restart; fixes an issue where make start could fail if the goalert-postgres container exists but not currently running
• added a SIZE= parameter for make regendb -- make regendb SIZE=0.1 will have 10% the normal data make regendb SIZE=10 will have 10x
• fixed a race condition in the region code that could cause a startup crash the first time GoAlert starts on a new DB with multiple engine instances
• fixed a shutdown panic when GoAlert shuts down before the HTTP server is started
• deleted the slowproxy devtool in favor of an open source alternative speedbump
• fixed a bug in the engine message module where it would release ALL advisory locks instead of just the message lock
• fixed an initial startup bug where the keyring would fail to start due to null time values
• switched the limit reset from truncate to delete from so it is caught by switchover triggers
• added documentation for the various advisory lock values
• added convenience methods for sql.DB and driver.Connector to the util/sqldrv package
• fixed a bug with error checking in the sqlutil.Listener where it would fail to exit on context cancellation
• updated notices to use a new toSeverity method that will take the various severity inputs and output the standard set of color values (removes the need to map them everywhere)
• fixed a bug in the contact method verification dialog that would inform the user to text "START" to ... when the FROM-number is unavailable. It will now omit the suggestion as intended in this case.