Debugger: Introduce convenience GdbMi::{toUtf8,toLatin1} functions

Change-Id: I10ec8cdca5aa2c54a5ed557b3c2ddbfd3855c796
Reviewed-by: hjk <hjk121@nokiamail.com>
Debugger: Use GdbMi convenience functions

Change-Id: I3c9a4df6b297ddfcce09cf438e42f1d666e910aa
Reviewed-by: hjk <hjk121@nokiamail.com>