Move ale#handlers#ruby#EscapeExecutable to ale#ruby#EscapeExecutable

This function is generally applicable to Ruby, not just handling linter
output.

autoload/ale/ruby.vim

@@ -74,3 +74,10 @@ function! ale#ruby#HandleRubocopOutput(buffer, lines) abort
     return l:output
 endfunction
 
+function! ale#ruby#EscapeExecutable(executable, bundle_exec) abort
+    let l:exec_args = a:executable =~? 'bundle'
+    \   ? ' exec ' . a:bundle_exec
+    \   : ''
+
+    return ale#Escape(a:executable) . l:exec_args
+endfunction