lsp: Identify language servers by their configuration (#35270)

- **WIP: reorganize dispositions**
- **Introduce a LocalToolchainStore trait and use it for LspAdapter
methods**

Closes #35782
Closes #27331

Release Notes:

- Python: Improved propagation of a selected virtual environment into
the LSP configuration. This should the make all language-related
features such as Go to definition or Find all references more reliable.

---------

Co-authored-by: Cole Miller <cole@zed.dev>
Co-authored-by: Lukas Wirth <lukas@zed.dev>

crates/extension_host/src/extension_host.rs

@@ -1275,6 +1275,7 @@ impl ExtensionStore {
                         queries,
                         context_provider,
                         toolchain_provider: None,
+                        manifest_name: None,
                     })
                 }),
             );