Request to export TXml parser as a Util

[Vasanthavanan-Devarajan]

Have you read the FAQ and checked for duplicate open issues?
Yes

Is your feature request related to a problem? Please describe.

Background on Manifest Preprocessing Changes:
With manifestPreprocessor being deprecated, I've migrated to using manifestPreprocessorTXml. However, this introduces a key difference - manifestPreprocessorTXml returns XML nodes instead of XML documents as previously returned by manifestPreprocessor.

Current Challenge:
To parse these XML nodes, the ideal approach would be to use Shaka's existing TXml utilities and functions. However, since these utilities aren't exported, I'm forced to reimplement the same XML parsing logic, which leads to:

• Duplicate code implementation
• Additional maintenance overhead

Describe the solution you'd like

Exposing Shaka's internal TXml utilities would allow for consistent and efficient XML parsing for external manifest preprocessing implementations.

Describe alternatives you've considered

NA

Additional context

NA

Are you planning to send a PR to add it?
Yes

[avelad]

This is dangerous, because it forces us to maintain an external API for this module. I don't agree, but I'll let @joeyparrish and @tykus160 have their say.

[joeyparrish]

I agree. I don't think we want to export txml itself, because of the requirements of backward compatibility for exported interfaces. @Vasanthavanan-Devarajan, can you give us examples of what you want to do with these interfaces?