Add linechart custom formatter testcases for long strings, non-printable characters and unicode value formatter results
Add linechart custom formatter testcases for long strings, non-printable characters and unicode value formatter results

Signed-off-by: Xabier Larrakoetxea <30fb0ea44f2104eb1a81e793d922a064c3916c2f@gmail.com>

mum4k/termdash,mum4k/termdash