Expand tau_payroll to TxJ

[jdebacker]

This PR addresses Issue #1242 by allowing payroll taxes to vary by J.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 75.86207% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 75.49%. Comparing base (10d3577) to head (222ed85).

Files with missing lines	Patch %	Lines
ogcore/tax.py	66.66%	4 Missing ⚠️
ogcore/household.py	50.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1244      +/-   ##
==========================================
- Coverage   75.57%   75.49%   -0.08%     
==========================================
  Files          24       24              
  Lines        6124     6134      +10     
==========================================
+ Hits         4628     4631       +3     
- Misses       1496     1503       +7     

Flag	Coverage Δ
unittests	75.49% <75.86%> (-0.08%)	⬇️

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Files with missing lines	Coverage Δ
ogcore/__init__.py	100.00% <100.00%> (ø)
ogcore/aggregates.py	100.00% <100.00%> (ø)
ogcore/parameters.py	81.97% <100.00%> (+0.21%)	⬆️
ogcore/household.py	89.92% <50.00%> (-0.99%)	⬇️
ogcore/tax.py	96.89% <66.66%> (-2.49%)	⬇️

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[rickecon]

@jdebacker. Thanks for this. Merging now.