feat: add env_vars as input to run_sh

[adschwartz]

Description:

This change adds env_vars to the run_sh. Feature was requested in issue #2050. Example of used in practice:

def run(plan, args={}):
    result = plan.run_sh(
        run = "mkdir -p kurtosis && echo $EXAMPLE",
        image = "badouralix/curl-jq",
        env_vars = {
            "EXAMPLE": "this_is_a_test"
        },
    )

outputs:

Container images used in this run:
> badouralix/curl-jq - locally cached

> run_sh run="mkdir -p kurtosis && echo $EXAMPLE" image="badouralix/curl-jq" env_vars={"EXAMPLE": "this_is_a_test"}
Command returned with exit code '0' and the following output:
--------------------
this_is_a_test

--------------------

Starlark code successfully run. No output was returned.

Is this change user facing?

YES

References (if applicable):

Closes: #2050

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