Update codegen for breaking changes in pageable methods

[jhendrixMSFT]

Updated code model to have discrete types for ClientMethodOptions, PagerOptions, and PollerOptions from azure_core.
The constructor for Pager now requires a PagerContinuationKind argument that's used to determine the emitted generic type parameters.

[Copilot]

Pull request overview

This PR updates the code generation for pageable methods to support breaking changes in the azure_core library. The changes introduce discrete types for method options and update the Pager API to use a constructor that requires a continuation kind parameter.

Key Changes:

• Introduced discrete types (ClientMethodOptions, PagerOptions, PollerOptions) to replace generic ExternalType usage
• Updated Pager to include continuation kind as a generic type parameter when using continuation tokens
• Replaced Pager::from_callback with Pager::new and wrapped async callbacks in Box::pin

Reviewed changes

Copilot reviewed 8 out of 29 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
packages/typespec-rust/src/codemodel/types.ts	Added new type definitions for ClientMethodOptions, PagerOptions, PollerOptions with PagerContinuationKind support
packages/typespec-rust/src/tcgcadapter/adapter.ts	Updated method options creation to use new discrete types and set continuation kind for token-based paging
packages/typespec-rust/src/codegen/helpers.ts	Updated type declaration generation to emit correct generic parameters for Pager and PagerOptions based on continuation kind
packages/typespec-rust/src/codegen/clients.ts	Updated pageable method body generation to use Pager::new and Box::pin(async move)
packages/typespec-rust/src/codegen/use.ts	Added logic to import format types when using continuation token strategy
packages/typespec-rust/test/**/*.rs	Updated all generated test files with new Pager signatures and PagerOptions type parameters
packages/typespec-rust/test/Cargo.toml	Updated azure_core dependency to compatible version
packages/typespec-rust/package.json	Bumped version to 0.32.0
packages/typespec-rust/CHANGELOG.md	Documented breaking changes