Add HBA self calibration

This MR adds the following functionality:

1. HBA self-calibration can be enabled through selfcal to true and selfcal_strategy to 'HBA'.
2. When self-calibration is turned on, both HBA target solves are changed from 2 MHz chunks to a full-bandwidth solve with a smoothness constraint by default if num_SB_per_group is not set. This removes discreteness in the solutions and limits the amount of irreparable damage a mismatched skymodel from e.g. TGSS can do.
3. When self-calibration is turned on, one iteration of selfcal as raised in #39 (closed) is done. An image of the input data is made at full resolution (6'') after which a solve against the resulting model is done.

It also:

• adds proper support for scalarphase calibration at some parsing stages.
• exposes additional DP3 and WSClean parameters in their respective steps.
• updates the solve against TGSS to use DDECal instead of gaincal.
• updates the inner uv cut in the TGSS solve to 200 lambda, matching the inner cut used for TGSS ADR1.