Simplify the creation of outcome invokers

[martintmk]

Details on the issue fix or feature implementation

Adding CreateInvoker methods to ResilienceStrategyBuilderContext to simplify the creation and taking advantage of automatic type resolution.

No public API changes.

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 #1237 (6845288) into main (63853e2) will increase coverage by 0.07%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #1237      +/-   ##
==========================================
+ Coverage   82.84%   82.91%   +0.07%     
==========================================
  Files         262      262              
  Lines        6115     6141      +26     
  Branches      964      966       +2     
==========================================
+ Hits         5066     5092      +26     
  Misses        844      844              
  Partials      205      205              

Flag	Coverage Δ
linux	82.91% <100.00%> (+0.07%)	⬆️
macos	82.91% <100.00%> (+0.07%)	⬆️
windows	82.91% <100.00%> (+0.07%)	⬆️

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

Impacted Files	Coverage Δ
...rcuitBreakerResilienceStrategyBuilderExtensions.cs	100.00% <100.00%> (ø)
...ack/FallbackResilienceStrategyBuilderExtensions.cs	100.00% <100.00%> (ø)
...ging/HedgingResilienceStrategyBuilderExtensions.cs	100.00% <100.00%> (ø)
...rc/Polly.Core/ResilienceStrategyBuilder.TResult.cs	100.00% <100.00%> (ø)
src/Polly.Core/ResilienceStrategyBuilder.cs	100.00% <100.00%> (ø)
.../Retry/RetryResilienceStrategyBuilderExtensions.cs	100.00% <100.00%> (ø)
src/Polly.Core/Strategy/EventInvoker.cs	100.00% <100.00%> (ø)
src/Polly.Core/Strategy/GeneratorInvoker.cs	100.00% <100.00%> (ø)
src/Polly.Core/Strategy/PredicateInvoker.cs	100.00% <100.00%> (ø)
....Core/Strategy/ResilienceStrategyBuilderContext.cs	100.00% <100.00%> (ø)

[martintmk]

This PR will also help with #1236 where I can drop additional duplications.