Add daxpy example

[bernhardmgruber]

Daxpy is a very simple kernel that is memory-bound. Since the data structure is basically a vector of double precision values, it let's as explore mappings that change the in-memory manifestation of a single datatype. This includes BitPackedFloatSoA, Bytesplit, ChangeTyp, etc.

[codecov]

Codecov Report

Merging #450 (54df90a) into develop (0de88be) will not change coverage.
The diff coverage is n/a.

❗ Current head 54df90a differs from pull request most recent head ccc4aa0. Consider uploading reports for the commit ccc4aa0 to get more accurate results

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##           develop     #450   +/-   ##
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  Coverage    99.21%   99.21%           
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  Files           58       58           
  Lines         5218     5218           
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  Hits          5177     5177           
  Misses          41       41           

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