Better MicroPython stdio for REPL

[WebReflection]

This MR switches MicroPython stdio from linebuffer true to linebuffer false accordingly with Damien suggestion and tested already it makes the PyTerminal (REPL) work as expected.

This MR does the following:

• it forces always linebuffer to false
• it uses basically the exact same logic used internally in MicroPython to buffer the content and emit it as a whole once the end of line \n (char code 10) is passed along
• it passes all tests for both output and errors