[BENCHMARK] Create folder structure

[Irallia]

Part of #197
As we distinguish between short and long read calling, we need different benchmarks for both.
But they share part of the structure, thus I copied the existing long read workflows and made a first update.
With another PR I will add real short read benchmarks.

[codecov]

Codecov Report

Merging #198 (af5c0f7) into master (37ddaf7) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #198   +/-   ##
=======================================
  Coverage   98.32%   98.32%           
=======================================
  Files          18       18           
  Lines         838      838           
=======================================
  Hits          824      824           
  Misses         14       14           

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