Add cloud diagnostics

[trontrytel]

This PR:

• moves the existing 1M and 2M radar reflectivity and effective radius to a CloudDiagnostics module
• adds a simple constant effective radius function (based on ClimaParams)
• adds a wrapper for Lu and Hallet effective radius parameterization that assumes N=100 (allows it to be used with 0M and 1M schemes)

[szy21]

I didn't go through any equations but the code change looks good to me.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.60%. Comparing base (174ef92) to head (141ee90).
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #510      +/-   ##
==========================================
+ Coverage   95.58%   95.60%   +0.01%     
==========================================
  Files          41       42       +1     
  Lines        1609     1615       +6     
==========================================
+ Hits         1538     1544       +6     
  Misses         71       71              

Components	Coverage Δ
src	97.23% <100.00%> (+0.01%)	⬆️
ext	69.79% <ø> (ø)