This PR fixes the issue where vat deliver commands were not being sent from the control panel. Previously, the code only tested whether the payload was a kernel command that recognized the ping command. With this change, the deliver command is now supported, which enables sending the following actions:

• message
• notify
• dropExports
• retireExports
• retireImports
• changeVatOptions
• startVat
• stopVat
• bringOutYourDead

I excluded initVat and syscall because there is no current use case for triggering them manually.