Mark component methods that used as actions in markup

[alexprey]

Parse use: attributes in component markup and mark methods of that component with action flag.

Examples:

<script>
/**
 * This method must be marked as an `action`
 */
function svelteActionTest(node) {
   // ....
}
</script>

<!-- Must parse w/o issues -->
<div use:svelteActionTest>
</div>

<!-- Must parse w/o issues -->
<div use:svelteActionTest={{ id: 123 }}>
</div>

<!-- Must ignore this attribute -->
<Component use:svelteActionTest>
</div>