[Button] Consolidate se23 logic and styles (#10040)

### WHY are these changes introduced?

Resolves #9922.

### WHAT is this pull request doing?

Consolidates se23 beta logic and styles for `Button` and `_button.scss`.
Adds new styles where necessary in `Button.scss` to fix specificity
issues with styling.
Fixes Button tests.

### How to 🎩

[Storybook](https://5d559397bae39100201eedc1-uauurpoyku.chromatic.com/?path=/story/all-components-button--all)
[Prod
Storybook](https://storybook.polaris.shopify.com/?path=/story/all-components-button--all&globals=polarisSummerEditions2023:true)

> Things to tophat: UI and interactive states (i.e., focus, pressed,
hover) at different breakpoints

🖥 [Local development
instructions](https://github.com/Shopify/polaris/blob/main/README.md#local-development)
🗒 [General tophatting
guidelines](https://github.com/Shopify/polaris/blob/main/documentation/Tophatting.md)
📄 [Changelog
guidelines](https://github.com/Shopify/polaris/blob/main/.github/CONTRIBUTING.md#changelog)

### 🎩 checklist

- [x] Tested on
[mobile](https://github.com/Shopify/polaris/blob/main/documentation/Tophatting.md#cross-browser-testing)
- [x] Tested on [multiple
browsers](https://help.shopify.com/en/manual/shopify-admin/supported-browsers)
- [ ] Tested for
[accessibility](https://github.com/Shopify/polaris/blob/main/documentation/Accessibility%20testing.md)
- [ ] Updated the component's `README.md` with documentation changes
- [ ] [Tophatted
documentation](https://github.com/Shopify/polaris/blob/main/documentation/Tophatting%20documentation.md)
changes in the style guide