Add async reference support

[jonasctrl]

Change Summary

This PR adds support for asynchronous reference fields in the Typesense Go SDK. The async_reference field option allows documents to be indexed successfully even when the referenced document doesn't exist yet.

https://typesense.org/docs/29.0/api/joins.html#asynchronous-references

PR Checklist

• I have read and signed the Contributor License Agreement.

[kishorenc]

@jonasctrl

Can you please add a test for this?

[tharropoulos]

@jonasctrl Thank you for the contribution! Was this run using the generate command, or did you manually add that part in client's yaml file?

[jonasctrl]

@jonasctrl Thank you for the contribution! Was this run using the generate command, or did you manually add that part in client's yaml file?

I didn’t notice at first that the openAPI yaml was in separate repo, but I see that you already made the necessary commit quite recently tharropoulos/typesense-api-spec@eb2f854 🙏. I've did additional update to use latest code generated files (with small adjustments that were need to integrate them)

[jonasctrl]

@jonasctrl

Can you please add a test for this?

I could, but on second thought this only affects client-generated code for the go SDK and testing this feature flag doesn’t seem necessary since similar fields added previously aren’t covered either.

[tharropoulos]

@kishorenc