add database function for flagging data as PSF or REF

[mperrin]

FOr various use cases, including self-reference surveys and engineering analyses, we want to be able to manually say "use this PSF star as science" or vice versa. Need a function to make this easy.

database.set_obs_type("PSF", program=1234, obsnum=123)

Eventually might have other arguments in addition to the above.

[mperrin]

Requested by @juliengirard

[juliengirard]

even better (useful to characterize TA but also for MIRI where the relative TA position between SCI and PSF is super sensitive):

database.set_obs_type("PSF", program=1234, obsnum=123, sgd=1)

with the ability to select a certain SGD position (PATT_NUM keyword).
default would be all or '0', and then 1 to 9 would select a single SGD position.