Specify reports directory

[bensteinberg]

This should allow the specification of a base directory for reports from merging accounts, something like

invoke merge-duplicative-accounts --reports-dir=/tmp

[codecov[bot]]

Codecov Report

Merging #3329 (a4bab73) into develop (6f09766) will decrease coverage by 0.16%. The diff coverage is 0.00%.

@@             Coverage Diff             @@
##           develop    #3329      +/-   ##
===========================================
- Coverage    70.17%   70.02%   -0.16%     
===========================================
  Files           55       55              
  Lines         6977     6982       +5     
===========================================
- Hits          4896     4889       -7     
- Misses        2081     2093      +12     

Impacted Files	Coverage Δ
perma_web/tasks/dev.py	0.00% <0.00%> (ø)

... and 1 file with indirect coverage changes