Create QSGTexture as Rhi Render Target

What I need is drawing my content to a texture then used by qtquick item. For opengl, we have QQuickFramebufferObject and custom item like metaltextureimport/vulkantextureimport example. The latter can be more generic, but currently we need to write code for each gfx api like the examples. Using QRhi apis is an option and it works in my project(https://github.com/wang-bin/mdk-examples/blob/qrhi/Qt/qmlrhi/VideoTextureNodePriv.cpp), but QRhi is private. If we can create a render target QSGTexture via a public api, the code will be very simple, and it can be a replacement of QQuickFramebufferObject. Of cause for opengl we also need to know fbo id.