[FR](Primitives) Modal Component

### On which framework/platform would you like to see this feature implemented?

React

### Which UI component is this feature-request for?

Other

### Please describe your feature-request in detail.

I would like to be able to use a Modal component within Amplify UI without having to create my own.

### Please describe a solution you'd like.

Requested Modal Customizations:
- Title
- Content
- Footer/Action (where buttons go)
- Size
- Overlay color / opacity
- How overflow is handled
- Transition

Inspiration: https://mantine.dev/core/modal/

### We love contributors! Is this something you'd be interested in working on?

- [ ] 👋 I may be able to implement this feature request.
- [ ] ⚠️ This feature might incur a breaking change.

No implementation files, tests, or entry points are identified in the issue. Review the requested Modal customizations and the linked Mantine Modal for scope; done would mean an Amplify UI React Modal supporting the listed title, content, footer/action, size, overlay, overflow, and transition options.

Written by the indexing model from the issue text.