`@remotion/media`: Add HLS support via Mediabunny beta

Update mediabunny to 1.42.0-beta.4 which adds HLS reading support.
Detect .m3u8 URLs and use PathedSource + HLS_FORMATS for HLS inputs,
while keeping existing UrlSource + ALL_FORMATS for regular media files.
Update documentation to reflect HLS support across all relevant pages.

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