Add reflection helper SetProperty

[theunrepentantgeek]

What this PR does / why we need it:

As a part of writing an extension for goal-seeking KeyVaults, I need the ability to set a specific property via reflection.
I've pulled this out into a separate helper with thorough testing.

How does this PR make you feel:

If applicable:

• this PR contains tests

[codecov-commenter]

Codecov Report

Merging #3348 (d9f8c88) into main (f1a70a4) will decrease coverage by 0.01%.
The diff coverage is 69.04%.

❗ Current head d9f8c88 differs from pull request most recent head a07239f. Consider uploading reports for the commit a07239f to get more accurate results

@@            Coverage Diff             @@
##             main    #3348      +/-   ##
==========================================
- Coverage   54.50%   54.50%   -0.01%     
==========================================
  Files        1511     1511              
  Lines      633427   633469      +42     
==========================================
- Hits       345277   345252      -25     
- Misses     231724   231773      +49     
- Partials    56426    56444      +18     

Files	Coverage Δ
v2/internal/reflecthelpers/reflect_helpers.go	71.95% <69.04%> (-0.84%)	⬇️

... and 30 files with indirect coverage changes

[theunrepentantgeek]

/azp run

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