[libcalamares] Move Python wrapper

- Take the Python wrapper for GlobalStorage out of the GlobalStorage.h
   header and add it to PythonHelper instead, saving some work in
   all the cases that only GS is interesting, not the Python bits.

src/libcalamares/PythonHelper.cpp

@@ -19,6 +19,7 @@
 
 #include "PythonHelper.h"
 
+#include "GlobalStorage.h"
 #include "utils/Dirs.h"
 #include "utils/Logger.h"
 
@@ -390,5 +391,67 @@ Helper::handleLastError()
     return QString( "<div>%1</div>" ).arg( msgList.join( "</div><div>" ) );
 }
 
+Calamares::GlobalStorage* GlobalStoragePythonWrapper::s_gs_instance = nullptr;
+
+// The special handling for nullptr is only for the testing
+// script for the python bindings, which passes in None;
+// normal use will have a GlobalStorage from JobQueue::instance()
+// passed in. Testing use will leak the allocated GlobalStorage
+// object, but that's OK for testing.
+GlobalStoragePythonWrapper::GlobalStoragePythonWrapper( Calamares::GlobalStorage* gs )
+    : m_gs( gs ? gs : s_gs_instance )
+{
+    if ( !m_gs )
+    {
+        s_gs_instance = new Calamares::GlobalStorage;
+        m_gs = s_gs_instance;
+    }
+}
+
+bool
+GlobalStoragePythonWrapper::contains( const std::string& key ) const
+{
+    return m_gs->contains( QString::fromStdString( key ) );
+}
+
+
+int
+GlobalStoragePythonWrapper::count() const
+{
+    return m_gs->count();
+}
+
+
+void
+GlobalStoragePythonWrapper::insert( const std::string& key, const bp::object& value )
+{
+    m_gs->insert( QString::fromStdString( key ), CalamaresPython::variantFromPyObject( value ) );
+}
+
+bp::list
+GlobalStoragePythonWrapper::keys() const
+{
+    bp::list pyList;
+    const auto keys = m_gs->keys();
+    for ( const QString& key : keys )
+    {
+        pyList.append( key.toStdString() );
+    }
+    return pyList;
+}
+
+
+int
+GlobalStoragePythonWrapper::remove( const std::string& key )
+{
+    return m_gs->remove( QString::fromStdString( key ) );
+}
+
+
+bp::object
+GlobalStoragePythonWrapper::value( const std::string& key ) const
+{
+    return CalamaresPython::variantToPyObject( m_gs->value( QString::fromStdString( key ) ) );
+}
 
 }  // namespace CalamaresPython