Export every root level type

[yleflour]

Feature Description

Export every declared root level types in the core sdk, such as:

• ProviderMetadata
• TelemetrySettings

There may be more but I haven't had time to go through all of them

Use Cases

I'd like to be able to write wrappers and middlewares for the core ai-sdk.
Missing such export makes it a bit painful to implement them as I need to extract them from existing exported types.
Also, as I'm building a library, "ai" is imported as a peer dependency so I'm unable to patch it.

Additional context

No response