SMSDispatcher: Add option for sending pseudo-multipart SMSes

Serves as a workaround for devices that are otherwise unable to send
concatenated SMS messages on certain carrier networks, by providing the
option (enabled by the "telephony.sms.pseudo_multipart" property) to send
multipart messages as individual (not concatenated) messages.

For example, parts of Sprint's network hang on receipt of multipart SMSes
on devices (e.g., d2spr) that use the qcom SMSLock method in sending
multiple messages.  That is, the device waits for acknowledgment of the
first PDU before sending subsequent PDUs, while the network (incompatibly)
waits for subsequent PDUs before acknowledging the first.  While sending
the messages individually is suboptimal, it both works reliably and
matches stock ROM behavior.