Remove band_to_calc from analysis functions?

[hombit]

After by_band was implemented in #327, the band_to_calc argument in the analysis function looks redundant. Currently, a user can achieve the same behavior for a few bands with source filtering, and for each band with by_band. In fact, I believe it is worth having the ability to ignore the passband sometimes in order to apply certain types of analysis over all object's sources, as discussed in #325 and #323.

Here, I propose removing band_to_calc from analysis functions and not requiring the band column for them.

[hombit]

Additional suggestion: we can change batch(by_band: bool) to batch(by_band: bool | BandType | list[BandType]), where BandType is a column dtype for bands, typically str or int. So by_band would also filter bands to have a single band only, batch(by_band='g') or multiple, but not all, bands, batch(by_band=['g', 'r'])