DEV: Refactor watched words (#24163)

- Ignore only invalid words, not all words if one of them is invalid

- The naming scheme for methods was inconsistent

- Optimize regular expressions

app/serializers/site_serializer.rb

@@ -210,7 +210,7 @@ class SiteSerializer < ApplicationSerializer
   end
 
   def censored_regexp
-    WordWatcher.serializable_word_matcher_regexp(:censor, engine: :js)
+    WordWatcher.serialized_regexps_for_action(:censor, engine: :js)
   end
 
   def custom_emoji_translation
@@ -226,11 +226,11 @@ class SiteSerializer < ApplicationSerializer
   end
 
   def watched_words_replace
-    WordWatcher.word_matcher_regexps(:replace, engine: :js)
+    WordWatcher.regexps_for_action(:replace, engine: :js)
   end
 
   def watched_words_link
-    WordWatcher.word_matcher_regexps(:link, engine: :js)
+    WordWatcher.regexps_for_action(:link, engine: :js)
   end
 
   def categories