Cherrypick PR283 from dev/emc to main

[laurenchilutti]

Description

When cherry-picking the changes from PR #283 I noticed that model/fv_regional_bc.F90 should also be modified to have an axis type matching the precision that the dycore is built with and not hard-coded double precision.

Fixes # (issue)

How Has This Been Tested?

Tested with SHiELD on Gaea

Checklist:

Please check all whether they apply or not

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have made corresponding changes to the documentation
• [x] My changes generate no new warnings
• [x] Any dependent changes have been merged and published in downstream modules

[laurenchilutti]

Yes I think that we should also change the other register_field calls. I will make the changes and do some more testing.