Themed Icons: Introduce Utils::Icon

Instead of describing icons via file name or in the themed icons case
via
a string that is a list of mask/color pairs, we have now a class for it.

Icons are now listed in per-plugin *icons.h headers.

RunControl::m_icon was The only place left where an icon property was in
fact a string. This patch changes that member to be a Utils::Icon.

Change-Id: Ibcfa8bb25e6d2e330c567ee7ccc0b97ead603177
Reviewed-by: Eike Ziller <eike.ziller@theqtcompany.com>

src/plugins/debugger/debuggerruncontrol.cpp

@@ -58,6 +58,7 @@
 #include <utils/qtcprocess.h>
 #include <coreplugin/icore.h>
 #include <coreplugin/coreconstants.h>
+#include <coreplugin/coreicons.h>
 #include <qmldebug/qmldebugcommandlinearguments.h>
 
 #include <qtsupport/qtkitinformation.h>
@@ -114,7 +115,7 @@ DebuggerRunControl::DebuggerRunControl(RunConfiguration *runConfig, DebuggerEngi
       m_engine(engine),
       m_running(false)
 {
-    setIcon(QLatin1String(Core::Constants::ICON_DEBUG_START_SMALL));
+    setIcon(Core::Icons::DEBUG_START_SMALL);
     connect(this, &RunControl::finished, this, &DebuggerRunControl::handleFinished);
 
     connect(engine, &DebuggerEngine::requestRemoteSetup,