Star & PSF measurement quality

[cailmdaley]

Umbrella issue collecting star/PSF measurement-quality threads — as opposed to the star verification tests grouped under #765.

Sub-issues:

• ngmix: the reduced-χ² anomaly on stars (error model) #769 — ngmix reduced-χ² anomaly on stars (error model)
• HSM: measure PSF/star shapes directly in sky coords (use_sky_coords), drop the WCS re-transform #775 — HSM: measure PSF/star shapes directly in sky coords, drop the WCS re-transform
• Extend size of bright star masks [BUG] #662 — bright-star mask sizes
• [NEW FEATURE] diagnostics on setools star catalogue #585 — setools star-catalogue diagnostics

— Claude (Fable) on behalf of Cail