McuSupport: Store macros as part of McuSdkRepository

To support extending the macros and calling the
McuTargetFactory::expandVariables function statically, the macros are
added as part of the SdkRepository.

This commit also adds helper functions to extend macros other than the
ones created from the packages.

Change-Id: Ie7d2a9ad626782eec18738bdd3472ffd202e7a36
Reviewed-by: Rainer Keller <Rainer.Keller@qt.io>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/mcusupport/mcusupportoptions.h

@@ -8,6 +8,7 @@
 #include "settingshandler.h"
 
 #include <utils/environmentfwd.h>
+#include <utils/macroexpander.h>
 
 #include <QObject>
 #include <QVersionNumber>
@@ -30,11 +31,19 @@ namespace Internal {
 
 class McuAbstractPackage;
 
+using MacroExpanderPtr = std::shared_ptr<Utils::MacroExpander>;
+using Macros = QHash<QString, Utils::MacroExpander::StringFunction>;
+
 class McuSdkRepository final
 {
 public:
     Targets mcuTargets;
     Packages packages;
+
+    void expandVariables();
+    MacroExpanderPtr getMacroExpander();
+
+    static Macros *globalMacros();
 };
 
 class McuSupportOptions final : public QObject