Debugger: More memory management fixes.

DwarfImageDebugInfo:
- Type name/info entries weren't being freed properly.

BaseUnit:
- The array of entries itself was being destroyed, but not the actual
objects. Consequently none of the DIE objects were ever being freed.

CfaRuleSet:
- The register rules array wasn't being freed.

FileManager:
- References to entries weren't being released. Some more work remains to be
done here though, as a subset of these objects still have a non-zero ref
count in the end.

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.