Handle action edits before commands (#467)

The Dart analysis server sometimes sends actions with both 'command' and
'edit' fields. The command doesn't have any effect when triggered on
the server and seems to be informational.

Whenever there is an edit, assume it is sufficient for the action.

autoload/lsc/edit.vim

@@ -22,15 +22,15 @@ function! s:SelectAction(ActionFilter, result) abort
 endfunction
 
 function! s:ExecuteCommand(choice) abort
-  if has_key(a:choice, 'command')
+  if has_key(a:choice, 'edit') && type(a:choice.edit) == type({})
+    call lsc#edit#apply(a:choice.edit)
+  elseif has_key(a:choice, 'command')
     let l:command = type(a:choice.command) == type('') ?
         \ a:choice : a:choice.command
     call lsc#server#userCall('workspace/executeCommand',
         \ {'command': l:command.command,
         \ 'arguments': l:command.arguments},
         \ {_->0})
-  elseif has_key(a:choice, 'edit') && type(a:choice.edit) == type({})
-    call lsc#edit#apply(a:choice.edit)
   endif
 endfunction