support xml output for a decklink input

[dericed]

example:

<?xml version="1.0" encoding="UTF-8"?>
<dvrescue xmlns="https://mediaarea.net/dvrescue" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="https://mediaarea.net/dvrescue https://mediaarea.net/dvrescue/dvrescue.xsd" version="1.2.1">
    <creator>
        <program>dvrescue</program>
        <version>22.12.20231208</version>
        <library version="23.11">MediaInfoLib</library>
    </creator>
    <media ref="out.mkv" fromCapture="device://84:3c0a102a:00000000" deviceName="UltraStudio HD Mini" format="Matroska" size="9120000">
        <source video="sdi" audio="embedded" timecode="vitc"/>
        <stop method='user' extra='SIGINT'/>
        <frames count="76" pts="00:00:00.000000" end_pts="00:00:02.535866" size="720x486" video_rate="30000/1001" chroma_subsampling="4:2:2" audio_rate="48000" channels="2">
            <frame n="0" pos="0" pts="00:00:00.000000" tc="01:16:11:01" seqn="F"/>
            <frame n="75" pos="9000000" pts="00:00:02.502500" tc="01:16:13:16" seqn="F"/>
        </frames>
    </media>
</dvrescue>

This is the same as for dv, but removes abst and adds a few attributes (the source ones and deviceName. I'd like the same approach with tc_n.

Eventually, I'd like to add in some libavfilter generated metadata, such as the TAG:lavfi.signalstats.SATMAX.