Introduce `asdf.util.load_yaml` #2390

Job	Run time
asdf / Load tox environments	11s
astropy / Load tox environments	4s
stsci / Load tox environments	4s
third-party / Load tox environments	7s
stsci / gwcs (ubuntu-latest)	1m 6s
stsci / jwst (ubuntu-latest)	7m 50s
stsci / stdatamodels (ubuntu-latest)	2m 12s
stsci / stpipe (ubuntu-latest)	41s
stsci / roman_datamodels (ubuntu-latest)	1m 14s
astropy / asdf-astropy (ubuntu-latest)	2m 30s
astropy / specutils (ubuntu-latest)	1m 33s
third-party / weldx (ubuntu-latest)	2m 33s
third-party / sunpy (ubuntu-latest)	2m 10s
third-party / dkist (ubuntu-latest)	2m 47s
asdf / asdf-wcs-schemas (ubuntu-latest)	1m 14s
asdf / asdf-coordinates-schemas (ubuntu-latest)	1m 52s
	28m 8s

Provide feedback