HUGE_R to dsl Float type for mixed precision

[fmalatino]

Description
This commit makes HUGE_R a Float dsl type for mixed precision functionality

How Has This Been Tested?
Tested by implemented unit tests
Use in builds of pace and pySHiELD and their unit tests

Should be reviewed after PR 43 in NDSL

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules
• New check tests, if applicable, are included
• Targeted model if this changed was triggered by a model need/shortcoming

[FlorianDeconinck]

LGTM

[oelbert]

👍