[BLEmulator] Verify payload size and throw if necessary

[mikolak]

MTU must be same or bigger than:
Read: returned array size + 1
Write/Monitor: return array size + 3

Those numbers account for additional information sent in these operations and come from @dariuszseweryn

I can't find in the source code to get the mtu value from the connection.
The requestMtu() will get the invalid PDU error.
Any idea?

@mikolak

[mikolak]

How are you calling requestMtu()? Could you move this question to a separate issue?