Use `.tool-versions` file from `asdf` for node (and other tool) version detection

https://github.com/rubys/dockerfile-rails/blob/718a4ad457d4a1330cc39788bdf55a07531adbbd/lib/generators/dockerfile_generator.rb#L712

`.tool-versions` may also contain information about ruby, yarn, and python, java, awscli, azure-cli, elixir, etc.. versions formatted like...

```
ruby 3.2.0
nodejs 19.6.0
yarn 1.22.19
python 3.10.7 2.7.18
```

Start at lib/generators/dockerfile_generator.rb around line 712, where the current version detection is referenced. Read the surrounding generator logic and determine how `.tool-versions` entries for node and the other named tools should be recognized. Done means the generator uses the relevant versions from that file when producing its Dockerfile output.

Written by the indexing model from the issue text.