[Feature Request] Support `.tool-versions` files

[devmotion]

asdf-vm allows to specify project dependencies such as python, poetry, nodejs, ..., and julia in .tool-versions files. This is very convenient in particular in projects that involve multiple tools besides julia and when working on different projects with different versions of these tools.

The actions/setup-node Github action allows to specify the desired version of nodejs by providing the location of a .tool-versions file: https://github.com/actions/setup-node/blob/72c43c2d8fa01b0e1ca5fc3f8cb258c8d8bd286d/action.yml#L10-L11
A similar functionality was also requested for the actions/setup-python action: actions/setup-python#571 actions/setup-python#588

IMO a similar functionality (with a version-file input?) for julia-actions/setup-julia would be very useful:

• Currently asdf does not support Windows, but if one would like to run CI with windows one could install Julia with setup-julia instead, in a way that ensures that the installed Julia version is consistent with the .tool-versions file.
• Currently the official asdf Github action does not support installation of only a subset of plugins, but it would be easy to only install Julia with setup-julia if the .tool-versions file format would be supported.

[SaschaMann]

I like the idea, I'll take a look at implementing it.