Created request and response objects for sdk 2.x

[lalwani]

Added

• AuthContext: Request config that third party uses to pass relevant config information
• AuthDestination: Config for how the third party wants to use the SSO flow. InApp will use custom tabs. CrossApp will use first party apps in the order of priority provided
• AuthResponse: Response to the third party after completing the SSO flow
• AuthType: Whether it's auth code flow or pkce flow. Note - Implicit flow has been dropped from the old sdk
• CrossApp: List of available first party apps that could be used for SSO
• PrefillInfo: Profile information from the partner app to prefill in the Uber SSO flow
• AuthException: Describes the exception if login was not successful

[lalwani]

I have a personal preference of grouping the top-level definitions in a single file if they're small and closely related to each other. But that's just preference.

I'd like to keep it this way. To me it becomes easier in searching, referencing and more readable. Thanks for the suggestion.