Remove DesignKit package (#1886)

- Move button styles to Compound
- Rename text style to AuthenticationTextStyle as its only in the auth flow.
- Add the brand colour locally for now until its included in Compound.

* Update snapshots.

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Co-authored-by: Stefan Ceriu <stefan.ceriu@gmail.com>

NSE/SupportingFiles/target.yml

@@ -37,7 +37,6 @@ targets:
       - package: Kingfisher
       - package: Collections
       - package: Compound
-      - package: DesignKit
       - package: DeviceKit
       - package: DTCoreText
       - package: LRUCache