Track time spend in add_result

[jenshnielsen]

Track time spend in add_result of Datasaver and record as span attribute for each measurement run to allow comparison to total run time.

[codecov]

Codecov Report

❌ Patch coverage is 83.33333% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 59.77%. Comparing base (e6ba717) to head (a361885).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
src/qcodes/dataset/measurements.py	83.33%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #7705   +/-   ##
=======================================
  Coverage   59.77%   59.77%           
=======================================
  Files         352      352           
  Lines       31683    31688    +5     
=======================================
+ Hits        18937    18942    +5     
  Misses      12746    12746           

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