Sqlite: Improve transaction by inversion of control

Using a callable makes it possible to omit the commit call. It is now
called by the withDeferredTransaction and withImmediateTransaction
function.

Change-Id: I9b7bfa7e32f269fe8fcba2fe5e1218e73f5846d1
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Vikas Pachdha <vikas.pachdha@qt.io>

tests/unit/unittest/sqlitereadstatementmock.cpp

@@ -8,6 +8,7 @@
 SqliteReadStatementMockBase::SqliteReadStatementMockBase(Utils::SmallStringView sqlStatement,
                                                          SqliteDatabaseMock &databaseMock)
     : sqlStatement(sqlStatement)
+    , databaseMock(databaseMock)
 {
     databaseMock.prepare(sqlStatement);
 }