Debugger: Separate internal constants.

src/plugins/debugger/breakhandler.cpp

src/plugins/debugger/breakwindow.cpp

src/plugins/debugger/cdb/cdboptionspage.cpp

src/plugins/debugger/commonoptionspage.cpp

src/plugins/debugger/debugger.pro

src/plugins/debugger/debuggerconstants.h

src/plugins/debugger/debuggerengine.cpp

src/plugins/debugger/debuggerinternalconstants.h

src/plugins/debugger/debuggerplugin.cpp

src/plugins/debugger/debuggerrunner.cpp

src/plugins/debugger/disassembleragent.cpp

src/plugins/debugger/gdb/gdbengine.cpp

src/plugins/debugger/gdb/gdboptionspage.cpp

src/plugins/debugger/memoryagent.cpp

src/plugins/debugger/snapshothandler.cpp

src/plugins/debugger/snapshotwindow.cpp

src/plugins/debugger/sourceagent.cpp

src/plugins/debugger/stackwindow.cpp

src/plugins/debugger/watchhandler.cpp

src/plugins/debugger/watchwindow.cpp