Use language-client providers for Call Hierarchy and Workspace Symbols

[Colen Garoutte-Carson (Colengms)]

The extension manually registered Call Hierarchy and Workspace Symbol providers that used cpptools-specific protocol methods. The native language server now advertises and implements the corresponding standard LSP capabilities for both cpptools and mscppls.

This change:

• Removes the custom Call Hierarchy and Workspace Symbol provider classes.
• Uses vscode-languageclient’s built-in providers and standard LSP requests.
• Preserves Call Hierarchy cancellation, progress UI, telemetry, and file-detail presentation through middleware.
• Preserves localized workspace-symbol scope and suffix presentation using metadata supplied through WorkspaceSymbol.data.
• Moves the quiet Call Hierarchy request helpers out of the Providers directory.
• Moves the Go to Definition helper out of Providers, since it is an internal command helper rather than a registered provider.

No user-facing behavior is intended to change.

Validation:

• npm run compile
• npm run lint
• Companion native desktop and mscppls integration tests pass.

Compatibility:

This PR requires the companion native change. It should ship with a matching cpptools binary that advertises the standard capabilities and no longer exposes the replaced custom methods.