Migrate components to CSS Modules (#2163)

Author: connor-baer

.changeset/brave-bikes-nail.md

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+---
+'@sumup/icons': patch
+---
+
+Fixed the `IconsManifest` type.

.changeset/lucky-monkeys-arrive.md

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+---
+'@sumup/circuit-ui': major
+---
+
+Migrated all [stable](https://circuit.sumup.com/?path=/docs/introduction-component-lifecycle--docs) components from [Emotion.js](https://github.com/emotion-js/emotion) to [CSS Modules](https://github.com/css-modules/css-modules).
+
+The styles are bundled and exported as a single CSS file as `@sumup/circuit-ui/styles.css`. Refer to your framework's documentation on how to include the styles globally in your application.
+
+The CSS file includes the base styles, so the BaseStyles component has been removed.
+
+If you are only importing [stable](https://circuit.sumup.com/?path=/docs/introduction-component-lifecycle--docs) components and aren't using Emotion.js in your app, you can remove all Emotion.js-related dependencies.