Simplify and enhance the pipeline reloads

[martintmk]

Details on the issue fix or feature implementation

This change simplifies the API and allows listening to multiple reload tokens.

Essentially, the caller can now do:

services.AddResiliencePipeline("my-pipeline", (builder, context) =>
{
    context.EnableReloads<Options1>();
    context.EnableReloads<Options2>();
   
    // add strategies
});

Whenever Options1 or Options2 are changed, the pipeline is reloaded. Previously, the pipeline could listen only to a single options.

Enabled by #1511
Contributes to #1507

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 #1512 (ad5ba8a) into main (3c76e05) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #1512      +/-   ##
==========================================
+ Coverage   84.01%   84.02%   +0.01%     
==========================================
  Files         275      274       -1     
  Lines        6542     6547       +5     
  Branches     1022     1024       +2     
==========================================
+ Hits         5496     5501       +5     
  Misses        837      837              
  Partials      209      209              

Flag	Coverage Δ
linux	?
macos	84.02% <100.00%> (+0.01%)	⬆️
windows	84.02% <100.00%> (+0.01%)	⬆️

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Files Changed	Coverage Δ
src/Polly.Core/Registry/ConfigureBuilderContext.cs	100.00% <100.00%> (ø)
....Core/Registry/RegistryPipelineComponentBuilder.cs	100.00% <100.00%> (ø)
...ly.Core/Utils/Pipeline/PipelineComponentFactory.cs	100.00% <100.00%> (ø)
...c/Polly.Core/Utils/Pipeline/ReloadableComponent.cs	100.00% <100.00%> (ø)
...ions/Registry/ConfigureBuilderContextExtensions.cs	100.00% <100.00%> (ø)