Fix catching by value

Pointed out by LGTM.
Change-Id: I223655c728305f6f45b3738553da5b7d7a69e8c8
Reviewed-on: https://review.haiku-os.org/c/haiku/+/2134
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

Debugger: Split into core library and application.

- Add subfolder src/kits/debugger which contains the debugger's core
functionality and lower layers. Correspondingly add headers/private/debugger
for shared headers to be used by clients such as the Debugger application
and eventual remote_debug_server. Adjust various files to account for
differences as a result of the split and moves.
- Add libdebugger.so to minimal Jamfile.