Allow WithModel with Dispatch models

[kris-brown]

Dispatch models are special models that have the meaning of "just use dispatch". Previously one could index a method with a dispatch model, i.e. f[d](args...) = f(args...). However to be more consistent with normal models, we also need a f(::WithModel{Dispatch}, args...) = f(args...) method to be automatically generated for each theory operation.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.22%. Comparing base (92f194e) to head (61edcd6).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #197   +/-   ##
=======================================
  Coverage   92.22%   92.22%           
=======================================
  Files          39       39           
  Lines        2366     2367    +1     
=======================================
+ Hits         2182     2183    +1     
  Misses        184      184           

☔ 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.