Add support for EDDGridFromNcFiles to have variables with different dimensions

[ChrisJohnNOAA]

Description

This allows EDDGridFromNcFiles to have dataVariables with different dimensions/axisVariables. For requests for dataVariables with dimensions that don't apply, the value will be assigned to the missing value of the unused dimension.

Fixes #178

Type of change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)

Checklist before requesting a review

• I have performed a self-review of my code
• My code follows the style guidelines of this project
• 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
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes