Insert SCTE-35 Messages in Manifest to Communicate Adbreaks to MediaPackage

[Nfrederiksen]

MediaPackage will add Ad breaks and related tags to the output streams, based on the input stream's SCTE-35 messages.
Supported SCTE-35 messages are documented here: https://docs.aws.amazon.com/mediapackage/latest/ug/scte.html

Currently, no SCTE-35 messages are included in hls-pull-push's uploaded manifests.

We need to add SCTE-35 messages based on the original Ad metadata and generate an updated manifest.
Perhaps, we need to build a separate function to generate a manifest, instead of reusing the function GenerateMediaM3U8(...).
That way we don't need to make another update to eyevinn/hls-recorder

[birme]

I think the pull/push should only ensure to pass-through. It should be the source to accommodate for this, for example the VOD2Live channel engine.