The break key (key value 0x0) was used as switch key from guest serial
to hv console and guest serial could not receive break key. This blocked
some guest debugging features like KGDB/KDB, sysrq, etc.
This patch leverages escape sequence "<escape> + <break>" to send break to
guest and "<escape> + e" to switch from guest serial to hv console.
Tracked-On: #8583
Signed-off-by: Qiang Zhang <qiang4.zhang@intel.com>
Reviewed-by: Junjie Mao <junjie.mao@intel.com>