feat: videoplayback proxying

adds support for proxying videos through the instance
the support is configurable, and disabled by default

ythdd_inv_tl.py

@@ -3,7 +3,7 @@
 # -----
 # Translates requests sent through Invidious API at /api/invidious/
 # to use internal extractors.
-from flask import Response, request, redirect
+from flask import Response, request, redirect, url_for
 from markupsafe import escape
 from time import strftime, gmtime, time
 from ythdd_globals import safeTraverse
@@ -1045,4 +1045,6 @@ def lookup(data, req):
 			return notImplemented(data)
 
 	elif len(data) == 1:
+		if data[0] == "videoplayback":
+			return redirect(url_for('videoplaybackProxy', **req.args))
 		return stats() # /api/invidious/something