[mtv] Add mtv.it and extract series metadata (#156)

* New extractors: MTVItalia, MTVItaliaProgramma
* Extract fields: series, season_number, episode_number

Authored-by: nixxo

yt_dlp/extractor/extractors.py

@@ -732,6 +732,8 @@ from .mtv import (
     MTVServicesEmbeddedIE,
     MTVDEIE,
     MTVJapanIE,
+    MTVItaliaIE,
+    MTVItaliaProgrammaIE,
 )
 from .muenchentv import MuenchenTVIE
 from .mwave import MwaveIE, MwaveMeetGreetIE