Remove usage of virtual function QSafeLayoutResourceReader::readDataFromFile from constructor

There is a warning about the QSafelayoutReader::readData function which should be considered to fix.

The following warning is from the QSafeLayoutReader::readData. This function works as expected the function is a pure virtual function.

E:/teholapp/work/qtsaferenderer/src/saferenderer/qsafelayoutfilereader.cpp:88:5: Calling 'QSafeLayoutFileReader::readData'
E:/teholapp/work/qtsaferenderer/src/saferenderer/qsafelayoutfilereader.cpp:94:35: Call to virtual method 'QSafeLayoutFileReader::readDataFromFile' during construction bypasses virtual dispatch
E:/teholapp/work/qtsaferenderer/src/saferenderer/qsafelayoutfilereader.cpp:94:35: warning: Call to virtual method 'QSafeLayoutFileReader::readDataFromFile' during construction bypasses virtual dispatch [clang-analyzer-optin.cplusplus.VirtualCall]
1: Calling 'QSafeLayoutFileReader::readData' in E:/teholapp/work/qtsaferenderer/src/saferenderer/qsafelayoutfilereader.cpp:88
2: Call to virtual method 'QSafeLayoutFileReader::readDataFromFile' during construction bypasses virtual dispatch in E:/teholapp/work/qtsaferenderer/src/saferenderer/qsafelayoutfilereader.cpp:94
E:/teholapp/work/qtsaferenderer/src/saferenderer/qsafelayoutresourcereader.cpp:81:5: Calling 'QSafeLayoutResourceReader::readData'
E:/teholapp/work/qtsaferenderer/src/saferenderer/qsafelayoutresourcereader.cpp:88:35: Call to virtual method 'QSafeLayoutResourceReader::readDataFromFile' during construction bypasses virtual dispatch
E:/teholapp/work/qtsaferenderer/src/saferenderer/qsafelayoutresourcereader.cpp:88:35: warning: Call to virtual method 'QSafeLayoutResourceReader::readDataFromFile' during construction bypasses virtual dispatch [clang-analyzer-optin.cplusplus.VirtualCall]
1: Calling 'QSafeLayoutResourceReader::readData' in E:/teholapp/work/qtsaferenderer/src/saferenderer/qsafelayoutresourcereader.cpp:81
2: Call to virtual method 'QSafeLayoutResourceReader::readDataFromFile' during construction bypasses virtual dispatch in E:/teholapp/work/qtsaferenderer/src/saferenderer/qsafelayoutresourcereader.cpp:88