Benchmark metrics on PIPAL dataset

[jzakirov]

Is your feature request related to a problem? Please describe.
See dataset description: https://www.jasongt.com/projectpages/pipal.html

Shortly, its the largest human-rated set of images to date and the only one containing rich number of realistic distortions from GAN models.

Benchmarking metrics performance on this set can give a good estimate of their usefulness in GAN modes evaluation.

Describe the solution you'd like
Add new column to benchmark table

Additional context
Full dataset is not released. Only ~80% of data is available for now, the rest will be published in a month or so.

UPDATE: Public train set is released and can be downloaded https://drive.google.com/drive/folders/1G4fLeDcq6uQQmYdkjYUHhzyel4Pz81p-