Add back append_testlog to CIME/utils.py

[ekluzek]

The function append_testlog was removed from CIME/utils.py in 1fa26aa. I didn't see a reason for it in the log, but assume it likely was just because it might not have been referenced elsewhere in cime? However, CTSM relies on this function for the LILACSMOKE and SSPMATRIXCN SystemTest tests. In general this is something useful to have in order to have tests add extra output to the TestLog. So keeping it around allows SystemTests to easily add to the TestLog output which in principle is an important thing to allow.

[ekluzek]

@jedwards4b and @billsacks if this sounds acceptable, I'll do a PR for this shortly. It doesn't hurt anything, just adds some code currently only used for example in the CTSM LILAC tests.

To prevent this kind of thing in the future, I'll add a comment about this in the code for where it's needed. It would also be good to have a unit test for it in the cime testing. The latter is a little more involved -- but is the best thing for preventing this type of removal.

[jedwards4b]

No - it was moved from utils.py to status.py as noted in the PR. The correct action is to update from
import CIME.utils to import CIME.status

[ekluzek]

Awesome, thanks @jedwards4b I missed that comment. But, see it now

#4660 (comment)

Thanks for letting me know. I'll close this after I test it out.