[WIP] Add majority of logic for HLS reading support

hls-sketch.ts

@@ -0,0 +1,21 @@
+const hlsInput = new ManifestInput({
+	source: new UrlSource('https://example.com/playlist.m3u8'),
+	formats: [HLS],
+});
+
+const variants = await hlsInput.getVariants();
+const bestVariant = await hlsInput.getPrimaryVariant();
+const qualityVariant = await hlsInput.getVariantFor('1080p'); // In spirit
+
+bestVariant.tracks; // ?
+bestVariant.bitrate; // ?
+bestVariant.isLive(); // ?
+
+const input = variant.toInput(); // => Input
+const segments = variant.getSegments(); // => Segments[]?
+
+const segment = variant.getFirstSegment();
+segment.path; // => string (for example 'segment1.ts')
+segment.timestamp; // => 10
+segment.duration; // 5
+segment.toInput(); // => Input