[Service Bus] AmqpAnnotatedMessage followups

[HarshaNalluru]

a. Custom logic to calculate absolute_expiry_time

Make sure the other languages have this

(.NET and JS have it #14786 (comment))

b. Re-evaluate the AmqpAnnotatedMessage interface for sending

UPDATE: removing this from the list of things to do - AmqpAnnotatedMessage is considered an advanced flow where developers are assumed to be familiar with which fields are usable and not-usable when sending. The work item here is just to makes sure there is a test that attempts to resend a received AmqpAnnotatedMessage.

...Since some of the properties that are applicable for the receive side are not applicable for send side such as below
- deliveryCount #14786 (comment)
- deliveryAnnotations #14786 (comment)
- CreationTime (gets overridden even if set by user) #14786 (comment)
- AbsoluteExpiry (gets overridden even if set by user) #14786 (comment)

c. Message field validation

As part of a recent change message field validation was moved into toRheaMessage. The validation needs to cover the AMQP message code path as well.

[richardpark-msft]

Item "b" is up for debate - no other languages are planning on adding any particular validation here. The reasoning is that customers that are using this workflow are familiar with AMQP and will not be confused about which fields would be reasonably set for sending vs receiving. My current thought is to strike it from the list, provided we can properly send messages with those fields.

[richardpark-msft]

All work that was specifically for JS completed in a few PRs:

#15271: Reenabling the body type (temporarily disabled for 7.1.0 from the master branch
#15295: Adding in support for scheduleMessages()