Support custom paths for `.tool-versions`

What do you think about supporting a GHA option to use a different file than the default `.tool-versions` ?

Example:

```
...
steps:
- uses: action/checkout@v4
- uses: asdf-vm/actions/install@v2
with:
tool-versions-path: ./my/custom/path/.tool-versions
```

or

```
...
steps:
- uses: action/checkout@v4
- uses: asdf-vm/actions/install@v2
with:
tool-versions-path: ./.tool-versions.ci
```

This will allow users to manage tools differently in CI to avoid installing unnecessary development dependencies that someone may only need on their local machine.

Do you think that could be possible?

Thanks 😄

Start by tracing the asdf-vm/actions/install@v2 action and how it currently locates .tool-versions. Check the GitHub Actions input handling and workflow coverage, then define done as accepting tool-versions-path for both example paths while preserving the default behavior.

Written by the indexing model from the issue text.