Implement command line interface for Debugger

[anevilyak]

The debugger currently only has a graphical front end. In order for it to replace gdb as the primary system debugger, it needs a command line interface as well. The latter must not require any of the servers to be usable, so as to be able to debug things like app_server crashes.

[bonefish]

I need some recreational hacking. Assigning this to me for the time being.

[anevilyak]

Feel free! I'm working on crash reports and whatever other bugs diver finds in the meantime anyways, so I hadn't even started on this anyways, other than adding the command line option to request it.

[anevilyak]

Known missing features/commands as of hrev45032:

• Signal handling for e.g. aborting in-progress commands.
• Terminal process group handover for input/signals when Debugger starts another CLI app within the same terminal.
• Listing images and symbol/function lookup in images.
• Breakpoint/watchpoint commands.
• Source code retrieval/display.
• Typecasting.
• Alternate output formats for variables.

[luroh]

Moving Debugger related tickets out of R1 milestone (Prop #14).

[X512]

What is left here? Command line debugger is already working when critical service like app_server crashes.

[pulkomandy]

I think https://dev.haiku-os.org/ticket/8087#comment:3 is still up to date

[anevilyak]

Correct. It has the bare minimum to save a report and do some very cursory inspection, but it's really not practically usable yet for any serious debugging.