HybridCache stability and logging improvements

[mgravell]

Stability (i.e. when bad things happen, it should be as gentle as possible) and logging:

• implement ILogger logging of significant events
• add basic EventSource capture
• enforce MaximumPayloadBytes, fixes #5432
• ensure that instability of the underlying cache backend is not exposed to the caller
• handle [de]serialization failures appropriately
• enforce MaximumKeyLength (do not use cache for invalid keys)

Microsoft Reviewers: Open in CodeFlow

[joperezr]

Hey @mgravell, as FYI I have re-targeted this PR to main branch as that is now our 9.0 branch going forward. Nothing should change from your point of view.

[mgravell]

Pretty sure the CI failure is timing; will tweak tomorrow