ResilienceStrategyRegistry now uses context to configure the builder

[martintmk]

Details on the issue fix or feature implementation

Having just key as a parameter when configuring the builder was not enough and could cause some compatibility issues in the future. Using context is future-proof and allows us to add new members without breaking changes.

I have also fixed the order inconsistency; the builder is first followed by context in the provided callback.

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 #1242 (95c903c) into main (2b7fbf2) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #1242   +/-   ##
=======================================
  Coverage   82.79%   82.79%           
=======================================
  Files         264      265    +1     
  Lines        6096     6096           
  Branches      966      966           
=======================================
  Hits         5047     5047           
  Misses        844      844           
  Partials      205      205           

Flag	Coverage Δ
linux	82.79% <100.00%> (ø)
macos	82.79% <100.00%> (ø)
windows	82.79% <100.00%> (ø)

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

Impacted Files	Coverage Δ
src/Polly.Core/Registry/ConfigureBuilderContext.cs	100.00% <100.00%> (ø)
...ore/Registry/ResilienceStrategyRegistry.TResult.cs	100.00% <100.00%> (ø)
.../Polly.Core/Registry/ResilienceStrategyRegistry.cs	100.00% <100.00%> (ø)
...ependencyInjection/AddResilienceStrategyContext.cs	100.00% <100.00%> (ø)
...dencyInjection/PollyServiceCollectionExtensions.cs	100.00% <100.00%> (ø)