dotnetup: Support Windows Terminal profile configuration

## Summary

Windows Terminal allows configuring profiles through JSON settings files. We should explore supporting automatic configuration of Windows Terminal profiles to set up the dotnet environment so we can effectively work with `cmd` as well.

## Context

This came up during review of #52641 (`dotnetup print-env-script` command). While the current approach on Windows uses registry-based environment variables (which works across all shells), Windows Terminal profiles could provide a way to configure dotnet on a per-profile basis.

`cmd` can technically get a profile if run through the Terminal application via JSON settings. This could be useful for users who want per-terminal configuration rather than system-wide environment variables.

## Questions to explore

- How can we modify existing Windows Terminal profiles to set additional environment variables?

## Related

- #52641 - Implements `dotnetup print-env-script` which generates shell configuration scripts
- This is distinct from the current registry-based approach on Windows

cc @dsplaisted @baronfel