Add support for running shared graphs

[sebastianrath]

This PR adds two new features.

1. Added support for running shared graph urls directly from the args. The graph must be hosted on app.actionforge.dev.

actrun [shared-url]
actrun https://app.actionforge.dev/shared/bitter-sound-5a24209a.act

2. Running actrun straight from bash, without installation

curl -fsSL https://www.actionforge.dev/actrun.sh | bash -s -- <shared-url> [options]
curl -fsSL https://www.actionforge.dev/actrun.sh | bash -s -- https://app.actionforge.dev/shared/bitter-sound-5a24209a.act