Update default CLI repo folder and remove the warning message

[josephjclark]

Look no-one in the world wants to set their OPENFN_REPO_DIR env var - everyone just wants a sensible default.

This is fine, but it means printing an annoying warning we print for users (and in CI).

I've been thinking about this for a while. The CLI sets a repo dir to like /tmp/openfn/cli-repo or something. But we should use something a bit more OS specific, or just create a .openfn folder in the user's home dir.

We can probably just use this?

import { os } from 'node:os'
const homeDir = os.homedir();