base-modem: implement new modem-wide cancellable, and rework AT commands

Instead of the `_in_port()' variants, we'll provide more generic
`_full()' methods. These should be used either if we want to send commands
to a specific port, or if we want to use a specific user-provided GCancellable.

In addition to this user-provided GCancellable, we keep the internal modem-wide
one.

plugins/novatel/mm-broadband-bearer-novatel.c

@@ -171,7 +171,6 @@ connect_3gpp_qmistatus (DetailedConnectContext *ctx)
         "$NWQMISTATUS",
         3, /* timeout */
         FALSE, /* allow_cached */
-        NULL, /* cancellable */
         (GAsyncReadyCallback)connect_3gpp_qmistatus_ready, /* callback */
         ctx); /* user_data */
 
@@ -230,7 +229,6 @@ connect_3gpp (MMBroadbandBearer *self,
         "$NWQMICONNECT=,,,,,,,,,,",
         10, /* timeout */
         FALSE, /* allow_cached */
-        NULL, /* cancellable */
         (GAsyncReadyCallback)connect_3gpp_qmiconnect_ready,
         ctx); /* user_data */
 }
@@ -338,7 +336,6 @@ disconnect_3gpp_check_status (MMBaseModem *modem,
         "$NWQMISTATUS",
         3, /* timeout */
         FALSE, /* allow_cached */
-        NULL, /* cancellable */
         (GAsyncReadyCallback)disconnect_3gpp_status_complete,
         ctx); /* user_data */
 }
@@ -362,7 +359,6 @@ disconnect_3gpp (MMBroadbandBearer *self,
         "$NWQMIDISCONNECT",
         10, /* timeout */
         FALSE, /* allow_cached */
-        NULL, /* cancellable */
         (GAsyncReadyCallback)disconnect_3gpp_check_status,
         ctx); /* user_data */
 }

plugins/novatel/mm-broadband-modem-novatel.c

@@ -206,7 +206,6 @@ load_supported_modes (MMIfaceModem *self,
         "+WS46=?",
         3,
         FALSE,
-        NULL, /* cancellable */
         (GAsyncReadyCallback)supported_networks_query_ready,
         result);
 }
@@ -362,7 +361,6 @@ load_current_bands (MMIfaceModem *self,
         "$NWBAND?",
         3,
         FALSE,
-        NULL,
         (GAsyncReadyCallback)load_current_bands_done,
         result);
 }
@@ -424,7 +422,6 @@ set_bands (MMIfaceModem *self,
         cmd,
         3,
         FALSE,
-        NULL,
         (GAsyncReadyCallback)set_bands_done,
         result);