Drop OutcomeArguments struct

[martintmk]

Details on the issue fix or feature implementation

For context:
#1507 (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 #1513 (e771ba1) into main (8aa9df2) will increase coverage by 0.08%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #1513      +/-   ##
==========================================
+ Coverage   84.02%   84.10%   +0.08%     
==========================================
  Files         274      277       +3     
  Lines        6547     6581      +34     
  Branches     1024     1025       +1     
==========================================
+ Hits         5501     5535      +34     
  Misses        837      837              
  Partials      209      209              

Flag	Coverage Δ
linux	?
macos	84.10% <100.00%> (+0.08%)	⬆️
windows	84.10% <100.00%> (+0.08%)	⬆️

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

Files Changed	Coverage Δ
src/Polly.Core/PredicateBuilder.TResult.cs	100.00% <ø> (ø)
...CircuitBreaker/CircuitBreakerPredicateArguments.cs	100.00% <100.00%> (ø)
...CircuitBreaker/CircuitBreakerResilienceStrategy.cs	100.00% <100.00%> (ø)
...itBreaker/CircuitBreakerStrategyOptions.TResult.cs	100.00% <100.00%> (ø)
...ircuitBreaker/Controller/CircuitStateController.cs	100.00% <100.00%> (ø)
...ly.Core/CircuitBreaker/OnCircuitClosedArguments.cs	100.00% <100.00%> (ø)
...ly.Core/CircuitBreaker/OnCircuitOpenedArguments.cs	100.00% <100.00%> (ø)
src/Polly.Core/Fallback/FallbackHandler.cs	100.00% <100.00%> (ø)
.../Polly.Core/Fallback/FallbackPredicateArguments.cs	100.00% <100.00%> (ø)
.../Polly.Core/Fallback/FallbackResilienceStrategy.cs	100.00% <100.00%> (ø)
... and 19 more