Introduce samples folder

[martintmk]

Details on the issue fix or feature implementation

Closes #1291

• The samples folder includes completely separate style and formatting rules compared to main solution to be aligned with common .NET guidelines.
• It builds automatically because the cake script scans all solutions in the repo.
• Just basic examples, more advanced and detailed ones are in Polly-Samples repo.

Confirm the following

• I started this PR by branching from the head of the default branch
• I have targeted the PR to merge into the default branch
• I have included unit tests for the issue/feature
• I have successfully run a local build

[codecov]

Codecov Report

Merging #1295 (58b662a) into main (833ad99) will increase coverage by 0.00%.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #1295   +/-   ##
=======================================
  Coverage   83.28%   83.28%           
=======================================
  Files         263      264    +1     
  Lines        6299     6301    +2     
  Branches      994      997    +3     
=======================================
+ Hits         5246     5248    +2     
  Misses        844      844           
  Partials      209      209           

Flag	Coverage Δ
macos	?
windows	83.28% <ø> (+<0.01%)	⬆️

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see 9 files with indirect coverage changes

[martincostello]

Just some outstanding comments for Generic and Intro.

[martincostello]

Nice work!