Expose .messages, .toolsets types in top-level pydantic_ai to aid IDE auto-import

[moritzwilksch]

closes #2931

Expose all types from messages.py in pydantic_ai, except for the two deprecated ones to prevent a circular import.

[moritzwilksch]

@DouweM can you take a first look before I proceed with the other modules? Pulled type into top-level module, updated imports, updated examples. Excluded: 2 deprecated types, these are still only importable from pydantic_ai.messages.

[DouweM]

@moritzwilksch Looks great! Can you replace from pydantic_ai.messages import with from pydantic_ai import inside the docs directory as well, and then run make update-examples?

[moritzwilksch]

will do! do you prefer separate PRs for the other modules or should I continue here?

[DouweM]

@moritzwilksch I'm fine with you continuing in this PR

[DouweM]

@moritzwilksch Thanks Moritz! Can your revert the changes for .direct, though, please? The docs state The direct module provides low-level methods which wouldn't be correct anymore, and that's explicitly a non-standard more-limited way of using Pydantic AI, so I'd prefer to keep it in a separate module.

[moritzwilksch]

Done!