[iwara] Add support (#2652 #5840 #7785)

* [iwara] Add initial support
* [iwara] Add search support
* [iwara] Code cleanup
* [iwara] Small fixes and additions
* [iwara] Add tag support
* [iwara] Add mime-type to metadata
* [iwara] Refactor patterns/matching using urllib
* [iwara] Add unit tests
* [iwara] Update docs
* [iwara] Fix linting on older Python versions
* [iwara] update 'IwaraAPI' interface class
    - define endpoints inside methods
    - implement and use _call() and _pagination()
    - cache auth tokens
* [iwara] split and rename 'profile' extractor
    TODO:
    - update test results
    - simplify code
* [iwara] simplify '_user_params()' usage
* [iwara] update 'video' extractor
    and move user data extraction into 'yield_video'
* [iwara] update 'image' extractor
    and move user info extraction into 'yield_image()'
* [iwara] update 'playlist' extractor
* [iwara] update 'search' extractor
* [iwara] update 'tag' extractor
* [iwara] simplify 'yield_image' usage
    perform API calls to get full 'files' list inside the function
* [iwara] add video "image" test
* [iwara] provide 'date' metadata
* [iwara] simplify 'source()'
    remove urllib.parse usage
* [iwara] small optimizations
    * get("key", {}) -> get("key") or {}
    * split("…", 1) -> partition("…")
    * use f-strings for all patterns
* [iwara] add missing 'keyarg=1' to profile() memcache decorator
* [tests/iwara] update results
* [iwara] extract more 'user' metadata
* [iwara] update default format strings
    include 'date' in filenames to order them chronologically
* [iwara] restructure image/video handling
    - use less generators
    - make processing individual media items non-fatal
* [iwara] fix login and token handling
* [iwara] add 'favorite' extractor
* [iwara] add 'following' and 'followers' extractors

---------

Co-authored-by: Mike Fährmann <mike_faehrmann@web.de>

docs/configuration.rst

@@ -466,6 +466,7 @@ Description
     * ``idolcomplex``
     * ``imgbb``
     * ``inkbunny``
+    * ``iwara``
     * ``kemono``
     * ``mangadex``
     * ``mangoxo``

docs/gallery-dl.conf

@@ -413,6 +413,11 @@
             "sleep-request": "0.5-1.5",
             "videos": true
         },
+        "iwara":
+        {
+            "username": "",
+            "password": ""
+        },
         "kemono":
         {
             "username": "",

docs/supportedsites.md

@@ -517,6 +517,12 @@ Consider all listed sites to potentially be NSFW.
     <td>Games</td>
     <td></td>
 </tr>
+<tr>
+    <td>Iwara</td>
+    <td>https://www.iwara.tv/</td>
+    <td>Favorites, Followers, Followed Users, individual Images, Playlists, Search Results, Tag Searches, User Profiles, User Images, User Playlists, User Videos, Videos</td>
+    <td>Supported</td>
+</tr>
 <tr>
     <td>Keenspot</td>
     <td>http://www.keenspot.com/</td>