Support .tsa and .tsv file extensions when parsing MPEG2-TS manifests

[JulianDomingo]

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

What version of Shaka Player are you using?
Latest (4.3.4).

Can you reproduce the issue with our latest release version?
Yes.

Can you reproduce the issue with the latest code from main?
Yes.

Are you using the demo app or your own custom app?
Custom app.

If custom app, can you reproduce the issue using our demo app?
Yes.

What browser and OS are you using?
Chrome, 1.52.

For embedded devices (smart TVs, etc.), what model and firmware version are you using?
Google Nest Hub, 1.52.

What are the manifest and license server URIs?

https://frumos01.tivo.com/rolling-buffer/cnnhd/cnnhd/transmux/index.m3u8?ccur_fmt_type=ts

What configuration are you using? What is the output of player.getConfiguration()?

Default config.

What did you do?

1. Load above URL.
2. Content doesn't load successfully because the addSourceBuffer() call is passed an invalid mimetype (audio/MP2T). audio/MP2T is generated by the guessMimeType*() logic in HlsParser.

What did you expect to happen?

1. Load above URL.
2. Content loads successfully and creates a source buffer with the video/mp2t codecs.

What actually happened?

Shaka doesn't recognize the .tsa and .tsv file extensions as valid MPEG2-TS. However, these are valid: https://en.wikipedia.org/wiki/MPEG_transport_stream.