`aspire new` starter apps include gitignore for react but not .Net projects

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Is your feature request related to a problem? Please describe the problem.

After building and `git init`ing a new starter project created with `aspire new`, git wanted to commit files from `obj` directories:

### Describe the solution you'd like

I'd expect the starter apps created through `aspire new` to include appropriate `.gitignore` files.

### Additional context

The react front end does include a `.gitignore`. I did come across #1299 suggesting a decision was made to not include these files, but then why does the react template include a `.gitignore`?