This re-adds the parser for the trace-cmd text trace, after it got
dropped along with wlauto sub-tree. There are minor differences from the
old WA2 parser.
- Changed to work with devlib start/stop markers
- TraceCmdTrace renamed to TraceCmdParser
- The file path is now passed to the parse() method rather than
on creation.
- detect whether markers are present in the trace and do not filter
if they aren't
