Add a Qt WebEngine resource PAK file to include devtools_resources only

The shipped qtwebengine_resources.pak file is about 6.5MB. It includes devtools_resources that is about 4.2MB. Would like to suggest to remove devtools_resources from qtwebengine_resources.pak and add an additional resource PAK file to include devtools_resources only. In that way, the user can have an option to choose if bundle devtools_resources in their product.