Investigate use of baseline-averaging option to speed up imaging

This is a copy of the issue RAP-395 on the ASTRON Jira board.

Description

WSClean offers baseline-dependent averaging functionality, which may speed up imaging, especially in the final 100% data cycle of the Rapthor pipeline.

Scope of this ticket would be:

• Find a suitable (to first order) baseline averaging factor
• Compare imaging times with and without baseline averaging enabled

May be blocked by #119