Add ability to customize GDB port when auto-starting gdb server

[jonahgraham]

When starting a gdbserver (like openocd) connected to a multi-core SoC the gdb server may open multiple ports. This change allows user to configure which port GDB connect to rather than forcing GDB to connec to the first port.

TODO list:

• [ ] Get approval for this idea in #569
• [x] Save the new checkbox state properly
• [ ] Review wording of the checkbox and tooltip (at the moment it is a bit wordy and maybe not clear enough)
• [ ] Apply this same change to all the other TabDebugger.java files

Fixes #569

[jonahgraham]

Converted to draft and added a TODO list to description.

[ilg-ul]

wording of the checkbox

yes, this is a hard one. :-(

[ilg-ul]

wording of the checkbox

How about "In sync with the GDB server"?

[jonahgraham]

Replaced by solution #571