[extractor] Add _perform_login function (#2943)

* Adds new functions `_initialize_pre_login` and `_perform_login` as part of the extractor API
* Adds `ie.supports_login` to the public API

yt_dlp/extractor/hidive.py

@@ -35,18 +35,14 @@ class HiDiveIE(InfoExtractor):
         'skip': 'Requires Authentication',
     }]
 
-    def _real_initialize(self):
-        email, password = self._get_login_info()
-        if email is None:
-            return
-
+    def _perform_login(self, username, password):
         webpage = self._download_webpage(self._LOGIN_URL, None)
         form = self._search_regex(
             r'(?s)<form[^>]+action="/account/login"[^>]*>(.+?)</form>',
             webpage, 'login form')
         data = self._hidden_inputs(form)
         data.update({
-            'Email': email,
+            'Email': username,
             'Password': password,
         })
         self._download_webpage(