Add sms.send command to allow sending text messages via the paired Android device.
Changes:
- Add SmsManager class to handle SMS sending via Android SmsManager API
- Add ClawdisSmsCommand enum and Sms capability to protocol constants
- Wire sms.send command into NodeRuntime invoke handler
- Add SEND_SMS permission to AndroidManifest.xml
- Advertise sms capability when SEND_SMS permission is granted
The SMS capability is only advertised when the user has granted SEND_SMS
permission. Messages longer than 160 chars are automatically split into
multipart messages.
