Add support for PartitionedRateLimiter

[martintmk]

Details on the issue fix or feature implementation

Implements the following proposal that adds support for PartitionedRateLimiter:

#1365 (comment)

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 #1383 (0082137) into main (22df640) will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #1383      +/-   ##
==========================================
+ Coverage   83.68%   83.70%   +0.02%     
==========================================
  Files         269      270       +1     
  Lines        6429     6438       +9     
  Branches     1004     1005       +1     
==========================================
+ Hits         5380     5389       +9     
  Misses        840      840              
  Partials      209      209              

Flag	Coverage Δ
linux	?
macos	83.70% <100.00%> (+0.02%)	⬆️
windows	83.70% <100.00%> (+0.02%)	⬆️

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Impacted Files	Coverage Δ
...olly.RateLimiting/RateLimiterResilienceStrategy.cs	100.00% <100.00%> (ø)
.../RateLimiterResilienceStrategyBuilderExtensions.cs	100.00% <100.00%> (ø)
...c/Polly.RateLimiting/RateLimiterStrategyOptions.cs	100.00% <100.00%> (ø)
src/Polly.RateLimiting/ResilienceRateLimiter.cs	100.00% <100.00%> (ø)

[martincostello]

The changes look ok, but from the tests I don't understand how the rate limiter would partition on the HTTP context, for example, where the limit is intended to be per client on a particular strategy pipeline.

[martintmk]

The changes look ok, but from the tests I don't understand how the rate limiter would partition on the HTTP context, for example, where the limit is intended to be per client on a particular strategy pipeline.

Let me create an more complex issue test that demonstrates this in follow-up.