Add logic to remove <v Name> tags from webvtt

[well-actulily]

I have encountered .vtt files that include speaker information within <v Name> tags. The opening tags are not currently removed, but the closing ones are. Both should be removed during conversion.

00:00:15.431 --> 00:00:23:482
<v SFX>♪ <i>(syncopated percussion)</i></v>

00:00:23.982 --> 00:00:27.318
- <v Testerson>I've landed in the test environment
at quite an interesting time.</v>

00:00:27.318 --> 00:00:30.655
- <v ID>ANCHOR:</v>
<v Anchor>This is a test broadcast.</v>

00:00:30.822 --> 00:00:33.825
- <v Testerson>I just achieved two test results,
not even preliminary.</v>

[vevv]

Interesting case, thank you. Might be nice to convert those to proper SDH text at one point.