Make exception handling simpler

[JSkimming]

Issue #18 has requested better documentation on how to log exceptions. Looking at this, it's relatively complicated when having to implement the three methods of IAsyncInterceptor.

This PR is an investigation into a potentially easier solution.

[codecov-io]

Codecov Report

Merging #20 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master    #20   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files           4      5    +1     
  Lines         175    229   +54     
  Branches        3      7    +4     
=====================================
+ Hits          175    229   +54

Impacted Files	Coverage Δ
...ore.AsyncInterceptor/ProcessingAsyncInterceptor.cs	100% <ø> (ø)	⬆️
...stle.Core.AsyncInterceptor/AsyncInterceptorBase.cs	100% <100%> (ø)

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