Clean dirty state before checkout

[ofalvai]

Checklist

• I've read and followed the Contribution Guidelines
• step.yml and README.md is updated with the changes (if needed)

Version

Requires a MAJOR/MINOR/PATCH version update

Context

When running on self-hosted agents, a previous merge conflict could leave the working tree in a dirty state. The step needs to do a reset before the checkout.

Changes

• Detect if the working tree is dirty
• Do a reset and clean if so
• Handle errors gracefully and continue execution. It's possible that either a reset or a clean is enough, depending on the working tree state.

Investigation details

Decisions