Re-export serde_json::Value from core

[heaths]

Resolves #1687. As long as we use Value from core, should serde_json::Value ever make a breaking change to Value we can effectively vendor just that while continuing to pick up changes to the de/serializers.

[Copilot]

Pull Request Overview

This PR makes serde_json an optional dependency controlled by the json and xml features in typespec_client_core, and re-exports serde_json::Value as Value from both typespec_client_core and azure_core for easier consumption. The changes ensure that JSON-related functionality is only compiled when needed, improving modularity and compilation times for consumers that don't require JSON support.

Key changes:

• Made serde_json dependency optional, enabled by either json or xml features
• Re-exported serde_json::Value as a top-level type in both crates
• Added feature gates throughout the codebase to conditionally compile JSON-related code
• Updated all references to use the re-exported Value type instead of serde_json::Value directly

Reviewed Changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
sdk/core/typespec_client_core/Cargo.toml	Made serde_json optional and tied to json/xml features
sdk/core/typespec_client_core/src/lib.rs	Re-exported Value conditionally and added feature gate for Sealed trait impl
sdk/core/typespec_client_core/src/http/response.rs	Added conditional compilation for Response struct based on json feature
sdk/core/typespec_client_core/src/http/request/mod.rs	Added feature gates for JSON-related imports, methods, and types
sdk/core/typespec_client_core/src/http/method.rs	Simplified Display trait implementation to be unconditional
sdk/core/typespec_client_core/src/http/format.rs	Added feature gates for JsonFormat and its implementations
sdk/core/typespec_client_core/src/base64.rs	Added feature gates for JSON serialization/deserialization tests
sdk/core/typespec_client_core/CHANGELOG.md	Documented the new re-exported Value type
sdk/core/typespec/Cargo.toml	Made serde dependency required for xml feature
sdk/core/azure_core/src/lib.rs	Re-exported Value from typespec_client_core
sdk/core/azure_core/src/error/error_response.rs	Updated to use crate::Value instead of serde_json::Value
sdk/core/azure_core/benches/deserialization.rs	Updated comments and imports to use azure_core::Value
sdk/core/azure_core/CHANGELOG.md	Documented the new re-exported Value type