Add support for a provisioning apn.

When there is a provisioning apn, such as lwaactivate from AT&T it is
not necessary nor desireble to try to make network connections as
they will be no TCP ACK's to SYN messages, except for a limited set
of operator white listed addresses.

This is implemented by adding two commands CMD_IS_PRVISIONING_APN
and CMD_ENABLE_MOBILE_PROVISIONING. These are used by ConnectivityService
CheckMp and to know when we are connected to a provisioning apn and to
turn actually bring up the connection when the user needs to provision.

Also, incorporate the sEnableFailFastRefCounter change from klp to make
a singleton and remove the RuntimeException.

Bug: 10328264
Change-Id: I3925004011bb1243793c4c1b963d923dc2b00cb5