McuSupport: Separate toolchain file and compiler packages

Toolchain package represents information about compiler and toolchain
file (.cmake). This information is parsed from JSON and used for Kit
creation. This includes cmake variables, path to compiler. This patch
extracts information about toolchain file into separate McuPackage.

Change-Id: Id165bdc5afa5d7cf5b5c96620e11cb878254c181
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>

src/plugins/mcusupport/mcupackage.cpp

@@ -432,11 +432,6 @@ QString McuToolChainPackage::toolChainName() const
     }
 }
 
-QString McuToolChainPackage::cmakeToolChainFileName() const
-{
-    return toolChainName() + QLatin1String(".cmake");
-}
-
 QVariant McuToolChainPackage::debuggerId() const
 {
     using namespace Debugger;