feat: simpler setting of antenna diameters in uvdata new

[steven-murray]

Description

Motivation and Context

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)
• [ ] Documentation change (documentation changes only)
• [ ] Version change
• [ ] Build or continuous integration change

Checklist:

• [x] I have read the contribution guide.
• [x] My code follows the code style of this project.

New feature checklist:

• [x] I have added or updated the docstrings associated with my feature using the numpy docstring format.
• [ ] I have updated the tutorial to highlight my new feature (if appropriate).
• [x] I have added tests to cover my new feature.
• [x] All new and existing tests pass.
• [x] I have updated the CHANGELOG.