[FEATURE]: Anchoring should back-propagate the corrections to individual dithers

[thomaswilliamsastro]

Is your feature request related to a problem? Please describe.
Currently, the anchoring step only affects the final mosaics -- it should also apply these corrections to individual dithers. We've been ignoring this for now since anyone using those will just be using DOLPHOT which doesn't require them, but is a use case in some situations (e.g. remosaicking)

Describe the solution you'd like
Apply anchoring to dithers

This is motivated by some of the NGC891 stuff @jchastenet has been working on