Add missing CompletionItemKind

Reference: https://microsoft.github.io/language-server-protocol/specification

Author: yshui

rplugin/python3/LanguageClient/CompletionItemKind.py

@@ -17,6 +17,13 @@
  16: 'Color',
  17: 'File',
  18: 'Reference',
+ 19: 'Folder',
+ 20: 'EnumMember',
+ 21: 'Constant',
+ 22: 'Struct',
+ 23: 'Event',
+ 24: 'Operator',
+ 25: 'TypeParameter'
 }