Move module specific features out of base class

[sfe-SparkFro]

The LARA-R6 does not support the following AT commands:

SparkFun_u-blox_Cellular_Arduino_Library/src/sfe_ublox_cellular.h

Lines 135 to 136 in e5b3693

	const char UBX_CELL_MESSAGE_PDP_CONFIG[] = "+UPSD"; // Packet switched Data Profile configuration
	const char UBX_CELL_MESSAGE_PDP_ACTION[] = "+UPSDA"; // Perform the action for the specified PSD profile

SparkFun_u-blox_Cellular_Arduino_Library/src/sfe_ublox_cellular.h

Line 139 in e5b3693

const char UBX_CELL_NETWORK_ASSIGNED_DATA[] = "+UPSND"; // Packet switched network-assigned data

SparkFun_u-blox_Cellular_Arduino_Library/src/sfe_ublox_cellular.h

Lines 175 to 177 in e5b3693

	const char UBX_CELL_GNSS_REQUEST_TIME[] = "+UTIME"; // Ask for time information from cellular modem (CellTime)
	const char UBX_CELL_GNSS_TIME_INDICATION[] = "+UTIMEIND"; // Time information request status unsolicited indication
	const char UBX_CELL_GNSS_TIME_CONFIGURATION[] = "+UTIMECFG"; // Sets time configuration

Corresponding methods/structs/enums/etc. should be moved into sfe_sara_r5.h for now. If we add support for other modules that support those AT commands, then those should instead be moved into an intermediate class between the base and the module classes.