P3 collisions

[rorlija1]

• PR with geometric collision kernel between ice and liquid particles.
• Also attempted to implement collisions in src, but I have many doubts... I also did not have the chance to add any docs for collisions... see my comments and ask me anything! I used some of Anastasia's old code but changed/added things from MM2015, Cholette 2019, and Musil 1970 (a paper they reference).
• The rates run in KiD but very very slowly...

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.81%. Comparing base (05e2b1c) to head (4de3a31).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #442   +/-   ##
=======================================
  Coverage   96.80%   96.81%           
=======================================
  Files          41       41           
  Lines        1442     1445    +3     
=======================================
+ Hits         1396     1399    +3     
  Misses         46       46           

Components	Coverage Δ
src	98.73% <100.00%> (+<0.01%)	⬆️
ext	69.79% <ø> (ø)