kfp compiler can not use a docker context as a directory

[pahask8]

What happened:

Currently kfp compiler can not use a docker context as a directory, see the code link

with tempfile.TemporaryDirectory() as local_build_dir:
    dockerfile_rel_path = 'Dockerfile'
    dst_dockerfile_path = os.path.join(local_build_dir, dockerfile_rel_path)
    shutil.copyfile(dockerfile_path, dst_dockerfile_path)

What did you expect to happen:
I think it is good to support a docker context instead of just a relational path to a Dockerfile.

What steps did you take:
Here is my example of code:

import os
from kfp import compiler

os.environ["GOOGLE_CLOUD_PROJECT"] = "my-project"
os.environ["GOOGLE_APPLICATION_CREDENTIALS"] = "gcp.json"

build = compiler.build_docker_image(
    staging_gcs_path="gs://kfp-build-stage",
    target_image="gcr.io/mmy-project/kfp-build",
    dockerfile_path="/kubeflow_pipelines/docker_build/src/Dockerfile",
    timeout=600,
    namespace="kubeflow"
)

As a result, I can not build a docker image that requires a docker context.

Anything else you would like to add:
[Miscellaneous information that will assist in solving the issue.]

Will submit a pull request.

[pahask8]

Pull request https://github.com/pahask8/pipelines/pull/new/2014

[pahask8]

Could someone please take a look at #2015 ? Thank you

[Ark-kun]

Fixed by #1970