Use size_t instead of uint8_t for sysex length

[phjanderson]

The size of a sysex message should be typed size_t instead of uint8 to allow longer sysex messages. Currently increasing SYSEX_BUFFER_SIZE in Settings.hpp does not work as expected, changing the length type to size_t solves the problem and allows handling larger sysex messages.

[tttapa]

This has been addressed on the new-input feature branch that will eventually become version 2.0 when I have more time.

Control-Surface/src/MIDI_Parsers/MIDI_MessageTypes.hpp

Line 262 in 2d790de

uint16_t length;

I think 64 KiB should be enough to cover most use cases. The new-input branch also supports chunked SysEx messages, so you don't need a large buffer to be able to receive (or send) huge messages.