prowjob,env: add script to extract env vars from job

[dhiller]

What this PR does / why we need it:

Adds a script that extract the environment variables from a job and converts them into a set of export commands.

Example:

$ ./hack/export-job-env-vars.sh periodic-kubevirt-e2e-k8s-1.31-sig-storage-root
export KUBEVIRT_E2E_RUN_ALL_SUITES=true && export KUBEVIRT_QUARANTINE=true && export TARGET=k8s-1.31-sig-storage && export FEATURE_GATES=Root

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

Special notes for your reviewer:

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[brianmcarey]

Will this include env variables that are included in presets? You might have to create the prowjob with hack/mkpj.sh to get all env variables.

[dhiller]

good point - this script originated from a quick hack I did for someone asking to replicate the settings of the k/kubevirt lanes.

This PR is just to not lose it though - I could add this as a follow up, WDYT?

[dhiller]

To answer your question - no, it obviously will not include the presets :)

[dhiller]

Just noticed that this will not work as expected anyways - sorry for the noise, reverted to draft