Add Zigbee initial support for EmberZNet protocol

[s-hadinger]

Description:

[Experimental] Initial support for EmberZNet protocol (Sonoff Zigbee bridge). It only allows to send/receive messages to further develop the stack. Zigbee stack is not yet functional.

Added #define USE_ZIGBEE_ZNP and #define USE_ZIGBEE_EZSP to choose at compile time the Zigbee chip. ZNP is CC2530, EZSP is EFR32.

Added ZbEZSPSend <hex> command to send raw commands to EFR32. is the logical payload. The command automatically adds: escaping of reserved bytes (stuffing), pseudo-randomization for DATA frames, CRC16 calculation and EOF byte.

Added ZbEZSPReceived event to report low level received message.

Ex:

ZbEZSPSend C0
18:55:33 RSL: RESULT = {"ZbEZSPSend":"Done"}
18:55:34 ZIG: {"ZbEZSPReceived":"C1020B"}

Related issue (if applicable): fixes #8583 (please keep issue open)

Checklist:

• The pull request is done against the latest dev branch
• Only relevant files were touched
• Only one feature/fix was added per PR.
• The code change is tested and works on core ESP8266 V.2.7.1
• The code change is tested and works on core ESP32 V.1.12.2
• I accept the CLA.

NOTE: The code change must pass CI tests. Your PR cannot be merged unless tests pass