#4607 No conflicts with nvim-lspconfig by default

Default `g:ale_disable_lsp` to a new mode `'auto'` by default. With this
setting applied, ALE will now check for the presence of nvim-lspconfig
and automatically turn off particular LSP linters if already configured
via nvim-lspconfig.

For users that do not use `nvim-lspconfig`, everything should work as
before.

autoload/ale/references.vim

@@ -179,9 +179,7 @@ function! ale#references#Find(...) abort
     let l:column = min([l:column, len(getline(l:line))])
     let l:Callback = function('s:OnReady', [l:line, l:column, l:options])
 
-    for l:linter in ale#linter#Get(&filetype)
-        if !empty(l:linter.lsp)
-            call ale#lsp_linter#StartLSP(l:buffer, l:linter, l:Callback)
-        endif
+    for l:linter in ale#lsp_linter#GetEnabled(l:buffer)
+        call ale#lsp_linter#StartLSP(l:buffer, l:linter, l:Callback)
     endfor
 endfunction