Introduce RetryBackoffType.ExponentialWithJitter

[martintmk]

The issue or feature being addressed

Closes #1108

Details on the issue fix or feature implementation

Adding RetryBackoffType.ExponentialWithJitter retry delay type and making it a default one.

Adopted from:
https://github.com/Polly-Contrib/Polly.Contrib.WaitAndRetry/blob/master/src/Polly.Contrib.WaitAndRetry/Backoff.DecorrelatedJitterV2.cs

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-commenter]

Codecov Report

Merging #1176 (594c914) into main (24da172) will increase coverage by 0.03%.
The diff coverage is 100.00%.

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@@            Coverage Diff             @@
##             main    #1176      +/-   ##
==========================================
+ Coverage   83.38%   83.42%   +0.03%     
==========================================
  Files         272      273       +1     
  Lines        6315     6328      +13     
  Branches     1027     1028       +1     
==========================================
+ Hits         5266     5279      +13     
  Misses        844      844              
  Partials      205      205              

Flag	Coverage Δ
linux	83.42% <100.00%> (+0.03%)	⬆️
macos	83.42% <100.00%> (+0.03%)	⬆️
windows	83.42% <100.00%> (+0.03%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/Polly.Core/Retry/RetryConstants.cs	100.00% <ø> (ø)
...c/Polly.Core/Retry/RetryStrategyOptions.TResult.cs	100.00% <ø> (ø)
src/Polly.Core/Retry/RetryStrategyOptions.cs	100.00% <ø> (ø)
src/Polly.Core/Retry/RetryHelper.cs	100.00% <100.00%> (ø)
src/Polly.Core/Retry/RetryResilienceStrategy.cs	100.00% <100.00%> (ø)
.../Retry/RetryResilienceStrategyBuilderExtensions.cs	100.00% <100.00%> (ø)
src/Polly.Core/Utils/RandomUtil.cs	100.00% <100.00%> (ø)