fix(cart): add backward compatibility voicea data format

[mickelr]

COMPLETES #< INSERT LINK TO ISSUE >

This pull request addresses

We have two major customers (Davra, Instant Connect) who use the Closed Captions through the new V3 SDK already and are actively testing and migrating to the V3 SDK. They rely on these events and the payload format.

by making the following changes

add backward compatibility voicea transcript data format

Change Type

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update
• Tooling change
• Internal code refactor

The following scenarios where tested

< ENUMERATE TESTS PERFORMED, WHETHER MANUAL OR AUTOMATED >

I certified that

• I have read and followed contributing guidelines

• I discussed changes with code owners prior to submitting this pull request

• I have not skipped any automated checks

• All existing and new tests passed

• I have updated the documentation accordingly

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Make sure to have followed the contributing guidelines before submitting.

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[mkesavan13]

Looks good to me