Reduce noise in Key Vault README code samples

[heaths]

Uses the include_file::include_markdown!() macro to include otherwise non-compilable Rust code snippets from the README.md files.

[Copilot]

Pull Request Overview

This PR makes Key Vault README code samples compilable and testable by using the include_file::include_markdown!() macro. The changes allow README code snippets to be executed as part of the test suite, improving documentation accuracy and maintainability.

Key Changes

• Adds test files for secrets, keys, and certificates that execute README code snippets using the include_markdown! macro
• Updates README code blocks from rust no_run to rust ignore with named labels to enable extraction and testing
• Adds include-file workspace dependency and includes it in the three affected Key Vault crates

Reviewed Changes

Copilot reviewed 11 out of 12 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
sdk/keyvault/azure_security_keyvault_secrets/tests/readme.rs	New test file executing README code snippets for secrets client
sdk/keyvault/azure_security_keyvault_secrets/README.md	Refactored code samples to be testable with labeled rust ignore blocks
sdk/keyvault/azure_security_keyvault_secrets/Cargo.toml	Added include-file dev dependency
sdk/keyvault/azure_security_keyvault_keys/tests/readme.rs	New test file with custom rand module to override random number generation for deterministic testing
sdk/keyvault/azure_security_keyvault_keys/README.md	Refactored code samples to be testable with labeled rust ignore blocks
sdk/keyvault/azure_security_keyvault_keys/Cargo.toml	Added include-file and rand_chacha dev dependencies
sdk/keyvault/azure_security_keyvault_certificates/tests/readme.rs	New test file executing README code snippets for certificates client
sdk/keyvault/azure_security_keyvault_certificates/README.md	Refactored code samples to be testable with labeled rust ignore blocks
sdk/keyvault/azure_security_keyvault_certificates/Cargo.toml	Added include-file dev dependency
sdk/keyvault/assets.json	Updated assets tag to reflect test recording changes
Cargo.toml	Added include-file to workspace dependencies
Cargo.lock	Updated lock file with new dependencies and version updates