Debugger: introduce target endianness handling

Change-Id: I597a667de1461383ce9e96e8ea9902895cf80ec6
Reviewed-on: https://review.haiku-os.org/c/haiku/+/7073
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: Adrien Destugues <pulkomandy@pulkomandy.tk>

Debugger: implement parsing DW_FORM_implicit_const

For attributes with form DW_FORM_implicit_const, the attribute
specification contains a third part which is a signed LEB128
number. This value shall be used as the value of the attribute
when parsing the debug_info section.

Change-Id: I3e9aa3ba70b3aa05e6d2f570a1464966c38e4b1b
Reviewed-on: https://review.haiku-os.org/c/haiku/+/6980
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: Rene Gollent <rene@gollent.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.