Update MSP protocol

[klutvott123]

for compatibility with betaflight/betaflight#11112.

The changes are:

• Reads version number from status byte
• Updated error bit mask. It's now bit 7
• Read command from payload based on version number
• Check CRC only for old MSP implementation
• Removed zero fill for outgoing buffer
• Some cosmetics

These changes makes it work with betaflight/betaflight#11112 while still being compatible with the previous implementation. MSPv1 jumbo frames and MSPv2 is not implemented yet, but can be added when/if we need it. I have tested this with and without the PR, using TBS Tracer and Frsky Fport and can confirm that it works as it should.

For testing:
betaflight-tx-lua-scripts_1.5.0.zip