Introduce OutcomeResilienceStrategy and drop some internals

[martintmk]

Details on the issue fix or feature implementation

For both non-generic and generic strategies we use the same implementation. Ever bult-in strategy that handles the outcomes uses the same concepts.

• Generic ones are only handling a single T result
• Non-generic ones are handling the results as object

To unify both of these and not split implementations we have used the Invokers that wrap the delegates into usable form for these strategies.

I was thinking on how we can simplify this handling even more and came with generic OutcomeResilienceStrategy<T>. When deriving from this strategy, you can use delegates directly without any additional layers.

So for example:

• RetryResilienceStrategy<T> - handles only results of type T
• RetryResilienceStrategy<object> - handles all result types (non-generic strategy)

This also allows us to drop all internal invokers. So far, OutcomeResilienceStrategy<T> is kept internal, but we can make it public later.

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 #1330 (3d7838c) into main (47aef87) will decrease coverage by 0.13%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #1330      +/-   ##
==========================================
- Coverage   83.66%   83.54%   -0.13%     
==========================================
  Files         270      268       -2     
  Lines        6448     6400      -48     
  Branches     1010     1003       -7     
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- Hits         5395     5347      -48     
  Misses        844      844              
  Partials      209      209              

Flag	Coverage Δ
linux	83.54% <100.00%> (-0.13%)	⬇️
macos	?
windows	83.54% <100.00%> (-0.13%)	⬇️

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Impacted Files	Coverage Δ
.../Polly.Core/CircuitBreaker/Health/HealthMetrics.cs	100.00% <ø> (ø)
src/Polly.Core/OutcomeArguments.cs	100.00% <ø> (ø)
src/Polly.Core/ResilienceStrategyBuilderContext.cs	100.00% <ø> (ø)
...CircuitBreaker/CircuitBreakerResilienceStrategy.cs	100.00% <100.00%> (ø)
...rcuitBreakerResilienceStrategyBuilderExtensions.cs	100.00% <100.00%> (ø)
...ircuitBreaker/Controller/CircuitStateController.cs	100.00% <100.00%> (ø)
src/Polly.Core/Fallback/FallbackHandler.cs	100.00% <100.00%> (ø)
.../Polly.Core/Fallback/FallbackResilienceStrategy.cs	100.00% <100.00%> (ø)
...ack/FallbackResilienceStrategyBuilderExtensions.cs	100.00% <100.00%> (ø)
...Core/Hedging/Controller/HedgingExecutionContext.cs	100.00% <100.00%> (ø)
... and 8 more