Incorporate CAM changes to ncdata and MPAS-A version

[gdicker1]

This PR updates Externals.cfg to bring in the results of EarthWorksOrg/CAM PRs #21 and #22

[gdicker1]

Status of Sub-PRs:

• https://github.com/EarthWorksOrg/CAM/pull/21
• https://github.com/EarthWorksOrg/CAM/pull/22

Once both these PRs are merged (and tagged) this PR will be moved out of draft

[gdicker1]

I plan to merge this PR in about an hour, added reviewers just for visibility.

Though EWOrg/CAM 22 is "closed" it should have been detected as a "merge"