Remove typeHierarchyProvider workaround when lsp_types adds the field

[m-wells]

Context

The LSP 3.17 spec includes typeHierarchyProvider on ServerCapabilities, but lsp_types 0.97.0 omits it (despite including other 3.17 fields like callHierarchyProvider, inlineValueProvider, inlayHintProvider).

Current workaround

In LspClient::initialize, we deserialize the initialize response to serde_json::Value first, extract typeHierarchyProvider from the raw JSON, store it as supports_type_hierarchy: bool, then deserialize into InitializeResult. See:

• src/lsp/client.rs — supports_type_hierarchy field + supports_type_hierarchy() accessor
• src/main.rs — extract_capabilities takes a separate type_hierarchy: bool parameter
• src/bridge/handler.rs — enrich_symbol gates subtypes enrichment on client.supports_type_hierarchy()

When to remove

When lsp_types adds type_hierarchy_provider to ServerCapabilities:

1. Drop the supports_type_hierarchy field and accessor from LspClient
2. Deserialize initialize directly into InitializeResult again (remove the intermediate Value step)
3. Use caps.type_hierarchy_provider.is_some() like every other capability
4. Remove the extra type_hierarchy parameter from extract_capabilities

Upstream: https://github.com/gluon-lang/lsp-types