Make it easier to use commands with uv

[thomasjpfan]

Tracking issue

Related to flyteorg/flyte#5597

Why are the changes needed?

It's hard to use uv in commands. With this PR, using uv targets the install python environment and it's simple to use. For example, we can now write:

image_spec = ImageSpec(
    name="myimage",
    registry="localhost:30000",
    packages=["numpy"],
    commands=["uv pip install scikit-learn"],
)

What changes were proposed in this pull request?

With this PR the run_commands automatically mounts the

How was this patch tested?

I ran the following workflow:

from flytekit import task, workflow, ImageSpec

image_spec = ImageSpec(
    name="myimage",
    registry="localhost:30000",
    packages=["scikit-learn"],
    pip_extra_index_url=[
        "https://pypi.anaconda.org/scientific-python-nightly-wheels/simple"
    ],
    env={"UV_PRERELEASE": "allow"},
)


@task(container_image=image_spec)
def sklearn_version() -> str:
    import sklearn

    return sklearn.__version__


@workflow
def main() -> str:
    return sklearn_version()

[pingsutw]

looks great, but some tests are failing

[thomasjpfan]

@pingsutw Fixed it in https://github.com/flyteorg/flytekit/pull/2897/files/a4aa19755933d8998fb0797507c52fb74760a462..206c3f9618d70a98d57935c8517532b6f63f03db by updating the test to a regex.