Separate HLS audio and video streams

Allows:
  * The HLS player to propose an "Audio only" resolution
  * The live to output an "Audio only" resolution
  * The live to ingest and output an "Audio only" stream

 This feature is under a config for VOD videos and is enabled by default for lives

 In the future we can imagine:
  * To propose multiple audio streams for a specific video
  * To ingest an audio only VOD and just output an audio only "video"
    (the player would play the audio file and PeerTube would not
    generate additional resolutions)

This commit introduce a new way to download videos:
 * Add "/download/videos/generate/:videoId" endpoint where PeerTube can
   mux an audio only and a video only file to a mp4 container
 * The download client modal introduces a new default panel where the
   user can choose resolutions it wants to download

scripts/build/server.sh

@@ -2,7 +2,9 @@
 
 set -eu
 
-rm -rf ./dist ./packages/*/dist
+if [ -z ${1+x} ] || [ "$1" != "--incremental" ]; then
+  rm -rf ./dist ./packages/*/dist
+fi
 
 npm run tsc --  -b --verbose server/tsconfig.json
 npm run resolve-tspaths:server

scripts/dev/embed.sh

@@ -2,8 +2,8 @@
 
 set -eu
 
-npm run build:server
+npm run build:server -- --incremental
 
 npm run concurrently -- -k \
-  "cd client && ./node_modules/.bin/vite -c ./src/standalone/videos/vite.config.mjs build -w --mode=development" \
+  "cd client && ./node_modules/.bin/vite -c ./src/standalone/videos/vite.config.mjs dev" \
   "NODE_ENV=dev npm start"

scripts/i18n/create-custom-files.ts

@@ -82,7 +82,8 @@ const playerKeys = {
   'Disable subtitles': 'Disable subtitles',
   'Enable {1} subtitle': 'Enable {1} subtitle',
   '{1} (auto-generated)': '{1} (auto-generated)',
-  'Go back': 'Go back'
+  'Go back': 'Go back',
+  'Audio only': 'Audio only'
 }
 Object.assign(playerKeys, videojs)