[Core feature] Shell Task should support accessing secrets

[kumare3]

Motivation: Why do you think this is important?

As a user of shell task, i should be able to access secrets supplied to my task. This is also true for other context vars like execution_id

Goal: What should the final outcome look like, ideally?

    t = ShellTask(
        name="test",
        script="""
            export EXEC_ID={ctx.execution_id}
            export SEC={ctx.secrets.group.key}
            cat {inputs.f}
            echo "Hello World {inputs.y} on  {inputs.j}"
            """,
        inputs=kwtypes(f=CSVFile, y=FlyteDirectory, j=datetime.datetime),
    )

Describe alternatives you've considered

NA

Propose: Link/Inline OR Additional context

No response

Are you sure this issue hasn't been raised already?

• Yes

Have you read the Code of Conduct?

• Yes