feat(shell): add $PWD and $OLDPWD

[thijmv]

What's the problem this PR addresses?

Closes #1804.

How did you fix it?

I fixed it by adding a PWD and OLDPWD environment variable and updating it on every cd.

Checklist

• [x] I have read the Contributing Guide.

• [x] I have set the packages that need to be released for my changes to be effective.

• [x] I will check that all automated PR checks pass before the PR gets reviewed.

[thijmv]

@arcanis could you review the changes?