Jlink gdb support

[0xc0170]

I would like to add jlink gdb server.

There's already gdb class which needs a small update (at least localhost): https://github.com/project-generator/project_generator/blob/master/project_generator/tools/gdb.py#L71

The another missing part is definitions. I checked the mcu part can be extracted from iar (it's first word OGChipSelectEditMenu: state: ). Plus add this info for a target, because of this: The command to run jlinkgdbserver is -select USB -device mcu -if interface -speed speed_value. It's target dependent.