Add an option to create a new branch from the default branch if the specified ref does not exist

[Shion1305]

Problem

Currently, when using actions/checkout, specifying a ref that does not exist causes the action to fail. In some workflows, it would be more efficient if, when the specified branch does not exist, a new branch could be automatically created from the default branch.

Proposed Solution

I propose adding an auto-create option to actions/checkout. This option would allow the action to:

1. Checkout the default branch (e.g., main) if the specified ref does not exist.
2. Create a new branch with the specified ref from the default branch.

This behavior would only occur when the auto-create option is enabled, keeping the current behavior unchanged by default.

Example YAML

- name: Checkout code
  uses: actions/checkout@v3
  with:
    ref: 'feature-branch'
    auto-create: true