[fitnakedgirls] add support (#8671)

* [fitnakedgirls] add extractor

Add support for fitnakedgirls.com:
- Photo galleries (/photos/gallery/)
- Category pages (/photos/gallery/category/)
- Tag pages (/photos/tag/)
- Video posts (/videos/)
- Blog posts (/fitblog/)

Handles both newer (wp-block-image) and older (size-large) templates.

* simplify & fix

- use '_extract_title' method
- move '_pagination' into base class
- update 'FitnakedgirlsTagExtractor' pattern

* update docs/supportedsites

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

scripts/supportedsites.py

@@ -62,6 +62,7 @@ CATEGORY_MAP = {
     "fappic"         : "Fappic.com",
     "fashionnova"    : "Fashion Nova",
     "fikfap"         : "FikFap",
+    "fitnakedgirls"  : "FitNakedGirls",
     "furaffinity"    : "Fur Affinity",
     "furry34"        : "Furry 34 com",
     "girlswithmuscle": "Girls with Muscle",