Added support for cancellation tokens

[adamralph]

Plan of action

• Decide whether to change Func<..., CancellationToken, Task{...}> params to delegates with an optional token
  • it doesn't work
  • how many delegates would be required
• Consider uniform session - we just ignore the token in the IPipelineContext adapter
• Obsolete unit of work - obsolete unit of work #5854
• Revert token additions in transport seam changes - Remove CancellationToken from the new seam #5858
• Decide whether to adopt the analyzers approach for IHandleMessages<T> and IHandleTimeouts<T> - Analyzer & Fixer for IHandleMessages<T> #5853 - we will not
• Investigate why MessageHandler is public - @andreasohlund - it's used here
• Update to FastExpressionCompiler 2.0 - Update to FastExpressionCompiler 2.0 #5880
• Ensure internal behaviors implement more performant behavior interfaces - Ensure internal behaviors implement more performant behavior interfaces #5882
• introduce On... delegates - introduce OnMessage, OnError, and OnSatelliteMessage delegates #5889
• obsolete AbortReceiveOperation - Obsolete AbortReceiveOperation method #5896
• consider whether the context should have methods to link another token or replace the token - not for now, can be introduced in a minor if required
• remove async timer - remove AsyncTimer #5912
• Add token to all relevant APIs - CancellationToken support #5897
  • Introduce a token source when stopping the endpoint to use as the message session root token - Introduce a token source when stopping the endpoint to use as the message session root token #5911
  • confirm whether we should have an optional token on message session methods but not on receive pipeline methods
• Make all non-private tokens optional - Make CancellationToken parameters optional #5946
• Fix tests after Introduce OnCompleted to the transport seam #5936 (plus fixups) is done - Support onComplete in transport tests #5939
• Consider where else we should check the token and bail out early
  • When shutting down throw OperationCancelledException before handler invocation #5964
• Set the severity level of the new analyzer to suggestion in all test projects - oustanding PRs
• ensure the code that calls feature starts and stops makes sense wrt cancellation and the throwing of OperationCancelledException - support cancellation during feature startup #6050
• add obsoletes for all the methods we broke which take a Func<... Task> - Obsolete methods that accepted a func without a cancellation token #6054
  • find all the instances of Func<.... CancellationToken, Task> in the approval file and ensure there is an obsoleted equivalent without a token
• Remove reflection tests which were replaced with analyzers - Remove reflection tests now covered by Particular.Analyzers #6062
• Add an analyzer and code fixer for forwarding the context token - Forward CancellationToken analyzer and code fixer #5923

[andreasohlund]

add obsoletes for all the methods we broke which take a Func<... Task>

done, ticked the box

[DavidBoike]

Done!