SIM7070 and 7000SSL

New Features

• Added a separate set of commands for the SIM7000 to support SSL
  • Thank you to @FStefanni for most of this work
• Added support for the SIM7070/7080/7090 LTE-M/NB IoT modules
• Made a new module for NTP support
  • Thank you to @Bascy for this
• Add Bluetooth support for the SIM808
  • Thank you to @adrianca88
• Migrate from Travis CI to GitHub actions

Improvements

• Several small improvements to Sequans Monarch modules
  • Thank you to @ffontaine
• Check GPRS (in addition to EPS) for Quectel BG96
  • Thank you to @j3tm0t0
• Where sensible, reading saved configuration values from XBee's before attempting to write.
  • This is in effort to reduce writes to flash on the XBee's - the manual warns that excessive writing to flash may lead to instability or reduce the module's life-span.

Bug fixes

• Fix USSD for longer messages
  • Thank you to @yaroshd81