[extractors] Use new framework for existing embeds (#4307)

`Brightcove` is difficult to migrate because it's subclasses may depend
on the signature of the current functions. So it is left as-is for now

Note: Tests have not been migrated

yt_dlp/extractor/spotify.py

@@ -23,6 +23,7 @@ class SpotifyBaseIE(InfoExtractor):
         'ShowEpisodes': 'e0e5ce27bd7748d2c59b4d44ba245a8992a05be75d6fabc3b20753fc8857444d',
     }
     _VALID_URL_TEMPL = r'https?://open\.spotify\.com/(?:embed-podcast/|embed/|)%s/(?P<id>[^/?&#]+)'
+    _EMBED_REGEX = [r'<iframe[^>]+src="(?P<url>https?://open\.spotify.com/embed/[^"]+)"']
 
     def _real_initialize(self):
         self._ACCESS_TOKEN = self._download_json(
@@ -97,12 +98,6 @@ class SpotifyBaseIE(InfoExtractor):
             'series': series,
         }
 
-    @classmethod
-    def _extract_urls(cls, webpage):
-        return re.findall(
-            r'<iframe[^>]+src="(https?://open\.spotify.com/embed/[^"]+)"',
-            webpage)
-
 
 class SpotifyIE(SpotifyBaseIE):
     IE_NAME = 'spotify'