Partial Rhode Island EITC refundability pre-2015

[YichunRen]

Fixes: #5156

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.00%. Comparing base (cb92a56) to head (7c52776).
Report is 118 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5166      +/-   ##
==========================================
- Coverage   99.12%   99.00%   -0.13%     
==========================================
  Files        2592     2614      +22     
  Lines       37707    38070     +363     
  Branches      162      165       +3     
==========================================
+ Hits        37378    37691     +313     
- Misses        297      346      +49     
- Partials       32       33       +1     

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[PavelMakarchuk]

Since the structure changed post-2015 - would be need a new bool parameter to indicate that (we want the current EITC calculation to apply post 2015

[YichunRen]

There has been no structural change before or after 2015. Before 2015, the rate was 15%, and now it has increased to 100%. See (N) (2) in https://webserver.rilegislature.gov/Statutes/TITLE44/44-30/44-I/44-30-2.6.htm

[leehengpan]

Please take a look at the error in the test generated by this file.