Local shared subscriber's routing cache

[ajatprabha]

Proposed Changes

Cache the message routing of shared subscribers in-memory.

Types of Changes

• Bugfix (non-breaking change which fixes issue #XXXX)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation (correction or otherwise)
• Cosmetics (whitespace, styles...)
• DevOps (Build scripts, pipelines...)

Checklist

• I have read the CODE_OF_CONDUCT.md document
• All tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if needed)
• Any dependent changes have been merged and published in related repositories
• I have updated changelog (At the bottom of the release version)
• I have squashed all my commits into one before merging

Further Comments

Local shared subscriptions currently do not honor shared subscription groups properly.
It is recommended to use shared subscription topics only for shared subscription use-cases. Do not expect broker to route msgs for same topic to both shared subscribers and normal subscribers. It will only route to shared subscribers irrespective of shared subscription groups.