Update 6.6.0

Breaking change notice

This update introduces backwards-incompatible changes to the LoRaWAN stack - please see the updated examples.

• [CC1101] 3 New CC1101 Functions (#1038) (by @Crsarmv7l)
• [SX126x] Use millis for timeouts (#1013)
• Update ArduinoHal.h to make spi and friends protected (#1044) (by @jp-bennett)
• [LoRaWAN] Added pin maps (#1047) (by @matthias-bs)
• [LoRaWAN] Fix downlink crashes (#1049), remove redundant parameter (by @StevenCellist)
• [SX126x] Use predefined image calibration bands (#1051)
• [SX126x] Fix image calibration (#1051)
• [SX126x] Added public method to set PA ramp time (#1054)
• [MOD] SPI configuration interface rework (#1057)
• [SX127x] Fixed getRSSI overload for PhysicalLayer (#1064)
• Updated board definitions for the LoRaWAN Examples (#1052) (by @Velocet)
• Fix interrupt emulation in Raspberry Pi example
• [LR11x0] Added LR11x0 support (#679)
• [CC1101] Fix RSSI readout (#1077)
• Use RadioLibTime_t (aka unsigned long) when dealing with millis() and micros() (#1075) (by @Elizafox)
• [LoRaWAN] Improve PHY behaviour, update beginABP, bugfixes (#1080) (by @StevenCellist)
• examples/NonArduino/Tock: Support RISC-V and bump libtock-c (#1082) (by @alistair23)
• Fixed issues found by cppcheck
• [SSTV] Added image converter tool
• [LoRaWAN] Improve readability to better match documentation (by @StevenCellist)
• [LR11x0] Added support for WiFi scanning
• [SX128x] Added interface for interrupt-driven CAD (#1085)
• LR11x0: fix setDioAsRfSwitch argument count (by @bkleiner)
• Fixes overload warning when building with ESP IDF (#1089) (by @illysky)
• [SX126x] Add rounding when using custom image rejection (#1096)
• [LR11x0] Implemented v2 GNSS commands
• [LR11x0] Added firmware update support
• [AX25] Fix possible string truncation
• [STM32WL] Fix output ramp time configuration
• fix payload of DevStatusAns mac-command (by @pnxs)
• [LoRaWAN] Change session activation (#1093) (by @StevenCellist)
• Fixed SX128X checkOutputPower (by @lewisxhe)
• [SX128x] Fix check output power argument name
• LW examples updated for new initialisation / join sequence (#1104) (by @HeadBoffin)
• [CC1101] Make frequency range check bounds inclusive
• [LR11x0] Make regulator mode and Rx gain config public (#1108)
• [LR11x0] Implemented RF switch control