C#V2 v2.1.15681

- Add support for large text commands via upload
- Add methods to control ePaper fast refresh policy
- Add XY-MODEM upload support
- Add GIF encoding to the library for efficient pixmap upload
- Update Mbed-TLS lib to 4.2
- Fix encoding for triggerForcedCalibration() argument
- Fix very slow detection of faulty device
