[PixArt-Alpha] Introduce resolution binning (#5739)
* feat: add resolution binning
Co-authored-by: lawrence-cj <jschen@mail.dlut.edu.cn>
* rename
* debug
* add :test
* remove unused variable
* set resolution_binning to False.
---------
Co-authored-by: lawrence-cj <jschen@mail.dlut.edu.cn>
