Added center arg to F.affine and RandomAffine ops

[vfdev-5]

Related to #5204

Description:

• Added center arg to F.affine and RandomAffine ops
• tests

Example from #5204 (comment)

from PIL import Image
import math
import torchvision # >= 0.11

from torchvision.transforms import functional as F
interpolation = torchvision.transforms.InterpolationMode.NEAREST
fill = None

img = Image.new('RGB', (32,32), (255,255,0))
magnitude = .7

im_torch = F.affine(
    img, angle=0.0, translate=[0, 0], scale=1.0, shear=[math.degrees(magnitude), 0.0],
    interpolation=interpolation, fill=fill, center=[0, 0])

[facebook-github-bot]

💊 CI failures summary and remediations

As of commit 76dbebf (more details on the Dr. CI page):

---

💚 💚 Looks good so far! There are no failures yet. 💚 💚

---

This comment was automatically generated by Dr. CI (expand for details).

Please report bugs/suggestions to the (internal) Dr. CI Users group.

Click here to manually regenerate this comment.

[datumbox]

@vfdev-5 Thanks for the PR. The changes look good, I only added a comment for an unimplemented feature left in.

I think it would be useful also to document a bit the approach of this PR by adding references to specific papers or implementations that follow your approach for centering.

[datumbox]

LGTM, thanks @vfdev-5.