Get final state from pollers

[heaths]

Resolves #2757

[github-actions]

API Change Check

APIView identified API level changes in this PR and created the following API reviews

azure_core
azure_security_keyvault_certificates
typespec_client_core
typespec

[antkmsft]

This makes sense an at least looks worthy of a try, I think I should try to consume this from my codegen PR, integrate there, and see what we get, and if it looks good.

[Copilot]

Pull Request Overview

This PR enhances long-running operation (LRO) polling by enabling pollers to automatically fetch and return the final resource state. Previously, pollers only returned status monitors; users needed to manually fetch the final resource. Now, pollers implement IntoFuture, allowing direct await to get the final result.

Key Changes

• Pollers now fetch and return the final model automatically upon successful completion
• Added IntoFuture implementation for Poller to enable await syntax
• Updated test files to remove manual fetching after polling completes

Reviewed Changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
sdk/core/azure_core/src/http/poller.rs	Added IntoFuture implementation and PollerResult::Succeeded variant with target callback; added Format trait method and associated type to StatusMonitor
sdk/core/typespec_client_core/src/http/format.rs	Added deserialize method to Format trait for deserializing response bodies
sdk/core/typespec_client_core/src/http/response.rs	Added to_raw_response() method to create RawResponse from cloned data
sdk/keyvault/azure_security_keyvault_certificates/src/models.rs	Updated StatusMonitor implementation to include Format type and improved status parsing logic
sdk/keyvault/azure_security_keyvault_certificates/src/clients.rs	Added target fetching logic in begin_create_certificate and resume_certificate_operation to retrieve final certificate
sdk/keyvault/azure_security_keyvault_certificates/tests/certificate_client.rs	Simplified tests to use direct await instead of wait() followed by manual fetching
sdk/keyvault/azure_security_keyvault_certificates/README.md	Updated documentation examples to show simplified polling pattern
sdk/keyvault/azure_security_keyvault_certificates/CHANGELOG.md	Documented breaking change of removing wait() function
sdk/core/azure_core/examples/core_poller.rs	Added examples demonstrating both await and stream-based polling patterns
sdk/core/azure_core/examples/core_pager.rs	Added PageIterator example and documentation improvements
sdk/core/azure_core/src/http/pager.rs	Added comprehensive documentation with usage examples
sdk/core/azure_core/README.md	Updated LRO example to show simplified polling pattern
sdk/core/azure_core/CHANGELOG.md	Documented breaking changes and new features
sdk/keyvault/assets.json	Updated test assets tag

[RickWinter]

@heaths The doc comments should be made. Do you want to accept the recommendations or do you want to push updates from your branch?

[heaths]

@analogrelay @LarryOsterman I'm not too crazy about adding a function to Format, though it's convenient. I prototyped another way that effectively makes it an internal trait: #3259. Curious what you think. I would rather keep Format as a marker trait, but it's hard to ignore the convenience of adding a function to it. That said, another problem with the prototype is that it limits users to only Formats we define; though, I think that's reasonable in this case. /cc @RickWinter