Ban use of ==# or ==? in the codebase, and prefer is# or is? instead

ale_linters/matlab/mlint.vim

@@ -30,7 +30,7 @@ function! ale_linters#matlab#mlint#Handle(buffer, lines) abort
 
         " Suppress erroneous waring about filename
         " TODO: Enable this error when copying filename is supported
-        if l:code ==# 'FNDEF'
+        if l:code is# 'FNDEF'
             continue
         endif