[FR]: export data needed for starlark language server

### What happened?

https://github.com/withered-magic/starpls works and knows the Bazel standard library (e.g. `rule()`)

It runs `bazel info build-language` - https://github.com/bazel-contrib/SIG-rules-authors/issues/52#issuecomment-3498871876

We should have `aspect info build-language` to provide the same editor help when authoring AXL.

### Version

Development (host) and target OS/architectures:

Output of `bazel --version`:

Version of the Aspect rules, or other relevant rules from your
`WORKSPACE` or `MODULE.bazel` file:

Language(s) and/or frameworks involved:

### How to reproduce

```shell

```

### Any other information?

_No response_

Start by comparing the requested `aspect info build-language` entry point with Bazel's `bazel info build-language` behavior and the editor data consumed by starpls. Determine where Aspect CLI exposes info commands; done means the new command provides equivalent language-server help for authoring AXL.

Written by the indexing model from the issue text.