Add new test that uses CPS input data

[martinholmer]

This pull request adds a new test that is similar to the aggregate test in the existing test_pufcsv.py file and moves an existing test to the new test_cpscsv.py file.

There is no change in tax-calculating logic, and therefore, no change in tax results.

[codecov-io]

Codecov Report

Merging #1490 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1490   +/-   ##
=======================================
  Coverage   99.96%   99.96%           
=======================================
  Files          40       40           
  Lines        2806     2806           
=======================================
  Hits         2805     2805           
  Misses          1        1

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