some simplifications of assemblers. Still need to work out how to smp…

[cmhamel]

…ly matrix actions and neumann bcs and the overall public facing API.

[codecov]

Codecov Report

❌ Patch coverage is 67.25664% with 37 lines in your changes missing coverage. Please review.
✅ Project coverage is 66.55%. Comparing base (06701b0) to head (faf46e4).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
src/assemblers/Assemblers.jl	75.90%	20 Missing ⚠️
src/bcs/PeriodicBCs.jl	0.00%	17 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #227      +/-   ##
==========================================
- Coverage   67.35%   66.55%   -0.80%     
==========================================
  Files          58       58              
  Lines        2959     2987      +28     
==========================================
- Hits         1993     1988       -5     
- Misses        966      999      +33     

☔ 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.