Introduce support for the LilyGo T-Connect Pro (16MB flash, 8MB PSRAM).
Adds board definition (boards/t-connect-pro.json), PlatformIO environments (variants/lilygo_tconnect_pro/platformio.ini) and variant-specific target glue (variants/lilygo_tconnect_pro/target.{h,cpp}).
Includes a new ST7796 LCD display driver ( based on the existing and already included Adafruit SS7796S driver in SS77xx )
* BasChatMesh: new onContactRequest(), for PAYLOAD_TYPE_REQ handling.
* companion, repeater and room_server: now with basic 'plumbing' to handle REQ_TYPE_GET_TELEMETRY_DATA (0x03).
* dependency: added CayenneLPP to libdeps
* all target.* modules now with a stub 'sensors' object.