PLT-2077 Support CJK hashtags (#4555)

* Add Korean character ranges to exist CJK pattern

* Add constant for CJK hashtags
Becuase most of keywords in CJK are two characters

* Add CJK ranges to hashtag pattern to handle it.

* Fixes hashtag pattern to apply numbers at last

* Remove a wrong test case
`test_` shouldn't be a hashtag

* Fix hashtag regex to support standard unicodes

* Remove wrong escapes from regex

webapp/utils/text_formatting.jsx

@@ -11,7 +11,7 @@ import XRegExp from 'xregexp';
 
 // pattern to detect the existance of a Chinese, Japanese, or Korean character in a string
 // http://stackoverflow.com/questions/15033196/using-javascript-to-check-whether-a-string-contains-japanese-characters-includi
-const cjkPattern = /[\u3000-\u303f\u3040-\u309f\u30a0-\u30ff\uff00-\uff9f\u4e00-\u9faf\u3400-\u4dbf]/;
+const cjkPattern = /[\u3000-\u303f\u3040-\u309f\u30a0-\u30ff\uff00-\uff9f\u4e00-\u9faf\u3400-\u4dbf\uac00-\ud7a3]/;
 
 // Performs formatting of user posts including highlighting mentions and search terms and converting urls, hashtags,
 // @mentions and ~channels to links by taking a user's message and returning a string of formatted html. Also takes
@@ -342,7 +342,7 @@ function autolinkHashtags(text, tokens) {
         return prefix + alias;
     }
 
-    return output.replace(/(^|\W)(#[a-zA-ZäöüÄÖÜß][a-zA-Z0-9äöüÄÖÜß.\-_]*)\b/g, replaceHashtagWithToken);
+    return output.replace(XRegExp.cache('(^|\\W)(#\\pL[\\pL\\d\\-_.]*[\\pL\\d])', 'g'), replaceHashtagWithToken);
 }
 
 const puncStart = XRegExp.cache('^[^\\pL\\d\\s#]+');