Support receiving breaks

[jessebraham]

This issue was migrated from GitLab. The original issue can be found here:
https://gitlab.com/susurrus/serialport-rs/-/issues/116

In particular, to be able to set flag PARMRK in c_iflag so that a BREAK is expressed as a sequence of control characters:

When neither IGNBRK nor BRKINT are set, a BREAK
reads as a null byte ('\0'), except when PARMRK is set, in
which case it reads as the sequence \377 \0 \0.

https://man7.org/linux/man-pages/man3/termios.3.html

[DanielJoyce]

This a low level serial port library, we shouldn't do anything with the data. If you want to support this, it could go in a layer above.

Trying to wedge protocol support into the serial support is kinda why the serial internals of octoprint are a mess. Let's keep this seperate.