Add image transformer

[pingsutw]

TL;DR

Add an image transformer, so the task can return PIL.Image.Image as an output,

Type

• Bug Fix
• Feature
• Plugin

Are all requirements met?

• Code completed
• Smoke tested
• Unit tests added
• Code documentation added
• Any pending items have an associated Issue

Complete description

My example:

import io
from typing_extensions import Annotated

import requests

from flytekit import task, workflow, ImageSpec
import PIL.Image

new_flytekit = "git+https://github.com/flyteorg/flytekit.git@da9f6645bb5e99580e38d89ef6824b81a1054279"
image_spec = ImageSpec(base_image="python:3.8-slim-buster", packages=[new_flytekit, "pillow"], apt_packages=["git"], registry="pingsutw")


@task(enable_deck=True, container_image=image_spec)
def t1() -> PIL.Image.Image:
    url = "https://miro.medium.com/v2/resize:fit:1400/1*0T9PjBnJB9H0Y4qrllkJtQ.png"
    response = requests.get(url)
    image_bytes = io.BytesIO(response.content)
    im = PIL.Image.open(image_bytes)
    return im


@workflow
def wf():
    t1()


if __name__ == "__main__":
    wf()

Tracking Issue

flyteorg/flyte#4193

Follow-up issue

NA

[codecov]

Codecov Report

Attention: 47 lines in your changes are missing coverage. Please review.

Comparison is base (8dc26d2) 55.20% compared to head (bfa4597) 55.09%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1901      +/-   ##
==========================================
- Coverage   55.20%   55.09%   -0.12%     
==========================================
  Files         300      301       +1     
  Lines       22399    22445      +46     
  Branches     3368     3370       +2     
==========================================
  Hits        12366    12366              
- Misses       9869     9914      +45     
- Partials      164      165       +1     

Files	Coverage Δ
flytekit/experimental/eager_function.py	22.94% <ø> (ø)
...ins/flytekit-kf-pytorch/tests/test_elastic_task.py	100.00% <ø> (ø)
...gins/flytekit-mlflow/tests/test_mlflow_tracking.py	100.00% <100.00%> (ø)
...kit-deck-standard/flytekitplugins/deck/renderer.py	88.88% <0.00%> (ø)
flytekit/core/type_engine.py	27.77% <0.00%> (-0.06%)	⬇️
flytekit/types/file/image.py	0.00% <0.00%> (ø)

... and 1 file with indirect coverage changes

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[eapolinario]

Do you think it's worth adding a test where we use Annotated[PIL.Image]?

[eapolinario]

Nit: can you use enable_deck?

[pingsutw]

I can't find any other place using PIL.Image in flytkeit