Clean duplications around disposing the pipelines

[martintmk]

Details on the issue fix or feature implementation

Internally, PipelineComponent implemented both IDisposable and IAsyncDisposable that caused some duplications. Now it only implements IAsyncDisposable.

The registry still implements IDisposable and IAsyncDisposable for ease of use. We can afford sync-over-async because in most scenarios DisposeAsync will have sync implementation anyway.

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

Patch coverage: 100.00% and project coverage change: -0.06% ⚠️

Comparison is base (0cbc4c6) 83.99% compared to head (791a7c3) 83.93%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1530      +/-   ##
==========================================
- Coverage   83.99%   83.93%   -0.06%     
==========================================
  Files         279      279              
  Lines        6547     6523      -24     
  Branches     1023     1017       -6     
==========================================
- Hits         5499     5475      -24     
  Misses        839      839              
  Partials      209      209              

Flag	Coverage Δ
macos	83.93% <100.00%> (?)
windows	83.93% <100.00%> (-0.06%)	⬇️

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

Files Changed	Coverage Δ
...ore/Registry/ResiliencePipelineRegistry.TResult.cs	100.00% <ø> (ø)
...olly.Core/Utils/Pipeline/ComponentDisposeHelper.cs	100.00% <ø> (ø)
...re/Utils/Pipeline/ComponentWithDisposeCallbacks.cs	100.00% <ø> (ø)
...rc/Polly.Core/Utils/Pipeline/CompositeComponent.cs	100.00% <ø> (ø)
src/Polly.Core/Utils/Pipeline/ExternalComponent.cs	100.00% <ø> (ø)
src/Polly.Core/Utils/Pipeline/PipelineComponent.cs	100.00% <ø> (ø)
.../Polly.Core/Registry/ResiliencePipelineRegistry.cs	100.00% <100.00%> (ø)
...c/Polly.Core/Utils/Pipeline/BridgeComponentBase.cs	100.00% <100.00%> (ø)
...c/Polly.Core/Utils/Pipeline/ReloadableComponent.cs	100.00% <100.00%> (ø)

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