Function apply_clipboard_commands 

pub fn apply_clipboard_commands(
    events: MessageReader<'_, '_, ScriptCommandEvent>,
    clipboard: Option<NonSend<'_, ClipboardHost>>,
    pending: Local<'_, PendingClipboardReads>,
    out: MessageWriter<'_, PluginEvent>,
)

Carry out the clipboard commands a script queued, and deliver the reads that have an answer as clipboard_read_events.