[Issue 763][producer] Fix deadlock in Producer Send when message fails to encode.

[samuelhewitt]

Add tests for producer schema encode.

Fixes #763

Motivation

When using Producer, if the ProducerMessage.Value fails to encode using the producer's Schema, the code never returns when using producer.Send() and never executes the callback when using producer.SendAsync(). Additionally, the publishSemaphore that was Acquired is never released.

Modifications

When an error is returned by Schema Encode, release the Semaphore and execute the callback.

Verifying this change

• Make sure that the change passes the CI checks.

This change added tests and can be verified as follows:

• Added integration test with failure to encode schema

Does this pull request potentially affect one of the following parts:

If yes was chosen, please highlight the changes

• Dependencies (does it add or upgrade a dependency): no
• The public API: no
• The schema: no
• The default values of configurations: no
• The wire protocol: no

Documentation

• Does this pull request introduce a new feature? no

[chiragbparikh]

@merlimat @wolfstudy @sijie Can we please review the above PR ^^^

[chiragbparikh]

@lhotari could you please review the above PR ^^^