Add ability to specify output array and footprint in reproject_and_coadd

[astrofrog]

This extracts part of #351

[codecov]

Codecov Report

Merging #387 (097327f) into main (9a5d2d2) will decrease coverage by 0.19%.
The diff coverage is 88.88%.

❗ Current head 097327f differs from pull request most recent head c72464a. Consider uploading reports for the commit c72464a to get more accurate results

@@            Coverage Diff             @@
##             main     #387      +/-   ##
==========================================
- Coverage   93.53%   93.35%   -0.19%     
==========================================
  Files          25       25              
  Lines         882      888       +6     
==========================================
+ Hits          825      829       +4     
- Misses         57       59       +2     

Files Changed	Coverage Δ
reproject/mosaicking/coadd.py	91.75% <88.88%> (-1.66%)	⬇️

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more