Send cursor column rather than column of start of word

Discussed on element.

I need some guidance to add tests.

Author: Aster89

ycmd/completers/language_server/language_server_protocol.py

@@ -689,7 +689,7 @@ def Range( request_data ):
   lines = request_data[ 'lines' ]
 
   if 'range' not in request_data:
-    start_codepoint = request_data[ 'start_codepoint' ]
+    start_codepoint = request_data[ 'column_codepoint' ]
     start_line_num = request_data[ 'line_num' ]
     start_line_value = request_data[ 'line_value' ]