[arcalive] add support (#5657 #7100)

* [arca.live] Add extractor skeleton

* [arcalive] update names and formatting

* [arcalive] implement initial file extraction code

* [arcalive] improve '_extract_media()' performance

compile and cache regex on demand

* [arcalive] improve image extraction

- extract 'data-originalurl' URLs if available
- replace URL query strings with 'type=orig'
- ignore emoticons by default

* [arcalive] update defaults

- include 'title' in filenames
- use 0.5-1.5s delay between requests

* [arcalive] use ext from 'data-orig' if available

* [arcalive] update docs/supportedsites

* [arcalive] add tests

* [arcalive] update 'board' extractor pattern

so it doesn't also match 'post' URLs

---------

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

docs/gallery-dl.conf

@@ -99,6 +99,12 @@
 
             "formats": ["pdf"]
         },
+        "arcalive":
+        {
+            "sleep-request": "0.5-1.5",
+
+            "emoticons": false
+        },
         "artstation":
         {
             "external" : false,