[Messaging] Remove v1 stack

[anuchandy]

Messaging libraries currently support both v1 and v2 stacks. Since v2 has been the default for SB for ~5 months and will be the default for EH in Jan/Feb, we should plan/draft-pr to remove the v1 stack to reduce code complexity, maintenance, and regression risks. This should be done before adding any major features. High-level tasks include:

1. Remove v1 stack types
2. Remove the delegators (types that wrap v1 and v2) and use v2 stack directly.
3. Remove the v1, v2 opt-in | opt-out configurations.
4. There will not be any public API breaking changes, but one-time binary breaking changes are expected, hence major version update for azure-core-amqp, SB and EH.