Debugger: Add skeleton for a debugger adapter protocol using engine

- Support the launch of an application
- Support continue/pause an application
- Support add breakpoint only after an app is launched
(I.e. preset breakpoints won't work)
- Support stop the debug session
- "Remove one break breakpoint" works but removes all breakpoints

ToDo:
- Polish the transition between stages
- Fix breakpoints handling
- Add support "Step in", "Step out" and "Step Over"

Task-number: QTCREATORBUG-27279
Change-Id: I5c32ce713f5a0f19cc3b9d995cbbadd8adf6a413
Reviewed-by: Artem Sokolovskii <artem.sokolovskii@qt.io>
Reviewed-by: hjk <hjk@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

src/plugins/debugger/debuggerruncontrol.cpp

@@ -70,6 +70,7 @@ DebuggerEngine *createPdbEngine();
 DebuggerEngine *createQmlEngine();
 DebuggerEngine *createLldbEngine();
 DebuggerEngine *createUvscEngine();
+DebuggerEngine *createDapEngine();
 
 static QString noEngineMessage()
 {
@@ -509,6 +510,9 @@ void DebuggerRunTool::start()
             case UvscEngineType:
                 m_engine = createUvscEngine();
                 break;
+            case DapEngineType:
+                m_engine = createDapEngine();
+                break;
             default:
                 if (!m_runParameters.isQmlDebugging) {
                     reportFailure(noEngineMessage() + '\n' +