Added a `--messaging-create-sms-with-text' command line option that works similar to
`--messaging-create-sms-with-data', except that it uses the content of the file as the
message text instead of data.
This allows creating mesasges containing both double and single quotes, which was not
possible with the existing `--messaging-create-sms' command line option.
This new method allows changing the SIM slot considered as primary,
when the modem supports multiple SIM slots.
The generic handling of this method will make sure that the modem
object and all its SIM objects are re-probed from scratch as soon as a
successful SIM slot switch happens.
Implementations may report MM_CORE_ERROR_EXISTS when the switch
doesn't need to happen (e.g. if the requested SIM slot is already the
active one).
