Size of ring buffer limiting size of I2C (and other) messages

The Wire library relies on the ring buffer object and the size of the buffer is hard-coded, therefore limiting the size of any outgoing or incoming messages. https://github.com/arduino/ArduinoCore-samd/blob/8f5e2eb58cb91d68c45449b00ed2a7aca794978b/cores/arduino/RingBuffer.h#L28

For instance, there should be no limitation to the size of messages in the I2C protocol, other than the available memory in the devices that are communicating. 64 bytes are not much when a lot of data needs to be transmitted, and splitting messages is not always an option.

Start with the RingBuffer definition at cores/arduino/RingBuffer.h#L28 and trace how the Wire library uses it for incoming and outgoing I2C data. Determine how the fixed 64-byte capacity constrains messages and define completion as supporting larger messages within the device's available memory without breaking existing Wire behavior.

Written by the indexing model from the issue text.