disable color coding from trace library when calling `set --vt100 off`

[jupe]

By default trace library uses colors for trace prints (vt100 control characters), but it should be disabled when calling cli command set --vt100 off.

default trace configuration: TRACE_MODE_COLOR | TRACE_ACTIVE_LEVEL_ALL | TRACE_CARRIAGE_RETURN

mbed_trace.c

but set --vt100 off doesn't disable color configuration from trace library, even it should..

ns_cmdline.c

so proposal is to call

mbed_trace_config_set(TRACE_ACTIVE_LEVEL_ALL | TRACE_CARRIAGE_RETURN);

when set --vt100 off -command is executed.

[jupe]

@RomanSaveljev @VeliMattiLahtela @SeppoTakalo @kuggenhoffen @teetak01