[WIP] Atomic collision model

[jjaraalm]

Working on merging in the atomic collision model. So far it builds, but is untested.

Remaining Items

• Run a test case with devel
• Add documentation to wiki
• Add an example - partially ionized reconnection

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.15%. Comparing base (49586ca) to head (421fdf9).
Report is 59 commits behind head on devel.

Additional details and impacted files

@@            Coverage Diff             @@
##            devel     #135      +/-   ##
==========================================
+ Coverage   83.11%   83.15%   +0.04%     
==========================================
  Files         118      118              
  Lines        7267     7267              
  Branches     1120     1120              
==========================================
+ Hits         6040     6043       +3     
+ Misses        754      752       -2     
+ Partials      473      472       -1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.