EZSP v14

[puddly]

This is going to be a huge change. Very WIP, only backup and restore is working.

• The command format for sending packets seems to have changed significantly.
• Parameters for most EZSP commands have been reordered.
• The error codes returned by the firmware have also completely changed and are not compatible with previous versions.
• Nothing is documented 😄 (Documentation for EmberZNet 8.0.0 and EZSP v14 SiliconLabs/simplicity_sdk#11)

[puddly]

This PR is in a state to be able to run successfully on my home network.

However, EmberZNet 8.0.0.0 is completely broken:

1. LQI and RSSI just do not contain valid values for any packet.
2. Unicast performance is abysmal and most sends do not succeed once more than a few packets have been sent at once.

This PR needs to be merged so that universal-silabs-flasher can enter the bootloader to downgrade from 8.0.0.0 but I'm otherwise not going to investigate EmberZNet 8.0.0.0 further.

[codecov]

Codecov Report

Attention: Patch coverage is 99.08676% with 4 lines in your changes missing coverage. Please review.

Project coverage is 99.38%. Comparing base (3657cf3) to head (52dae0b).

Files	Patch %	Lines
bellows/zigbee/application.py	92.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              dev     #631      +/-   ##
==========================================
- Coverage   99.72%   99.38%   -0.34%     
==========================================
  Files          75       79       +4     
  Lines        5017     5047      +30     
==========================================
+ Hits         5003     5016      +13     
- Misses         14       31      +17     

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[puddly]

Project coverage shrinks just a little bit with this PR but unfortunately there's no sensible way to actually deal with EZSP v14 command processing without rewriting all EZSP commands to use named parameters.

[Hedda]

Also see comments by Zigbee2MQTT/zigbee-herdsman ember developer Nerivec in SiliconLabs/simplicity_sdk#13