Excel OpenSpout exporter

[mhvis]

Thanks for merging the previous PR! I forgot to add a couple additional requested features to the export, namely a freeze row and AutoFilter.

So that's in this PR.

If this PR is good like this, could you make a new release? Then we can start using the new exporter.

Thanks in advance!

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.52%. Comparing base (879898d) to head (8569907).

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #333   +/-   ##
=======================================
  Coverage   94.52%   94.52%           
=======================================
  Files          37       37           
  Lines         968      968           
=======================================
  Hits          915      915           
  Misses         53       53           

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[curry684]

Thnx!