Introduce Parameter.remove_data()

[glatterf42]

Exactly the same as #159: this PR adds the Parameter.remove_data() functionality. Please see #159 for additional notes, as they apply to both PRs equally.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.5%. Comparing base (8eec6db) to head (a910bed).

Additional details and impacted files

@@                       Coverage Diff                       @@
##           enh/introduce-table-remove-data    #160   +/-   ##
===============================================================
  Coverage                             88.5%   88.5%           
===============================================================
  Files                                  223     223           
  Lines                                 8083    8113   +30     
===============================================================
+ Hits                                  7155    7185   +30     
  Misses                                 928     928           

Files with missing lines	Coverage Δ
ixmp4/core/optimization/parameter.py	93.3% <100.0%> (+0.2%)	⬆️
ixmp4/data/abstract/optimization/parameter.py	97.0% <100.0%> (+<0.1%)	⬆️
ixmp4/data/api/optimization/parameter.py	94.6% <100.0%> (+0.6%)	⬆️
ixmp4/data/db/optimization/parameter/model.py	97.3% <100.0%> (+0.1%)	⬆️
ixmp4/data/db/optimization/parameter/repository.py	96.7% <100.0%> (+0.5%)	⬆️
ixmp4/server/rest/optimization/parameter.py	97.2% <100.0%> (+0.3%)	⬆️