Add Duplication Rule to StyleLinter

### Description

In [Ally stylelint config](https://github.com/alleyinteractive/alley-scripts/tree/main/packages/stylelint-config), we should add an additional rule that would flag any duplication of properties.


It would involve adding` "declaration-block-no-duplicate-properties": true,` and `ignore: ["consecutive-duplicates-with-different-values"]` in the `.stylelintrc.json` settings.

StyleLinter Documentation found here https://stylelint.io/user-guide/rules/declaration-block-no-duplicate-properties/

### Use Case

When a developer is writing two identical properties in CSS, the linter should warn them that the first property will be overrided and effectively useless. If someone needs a duplicative property for a specific reason, they would have to disable stylelint for that line intentionally.

```
padding: 20px;
padding: 30px;
```

One concern is that it will start to flag css code that looks like:
```
.thing-that-renders-with-js {
/* critical:start */
opacity: 0;
/* critical:end */
opacity: 1;
}
```

Depending on how many errors like that are flagged, we may have to put a pin in this and have a broader discussion.