SolidLSP: Allow workspace folders to be flexibly configured across all language servers

that use the newly introduced InitializeParamsBuilder

- Add new configuration option `ls_workspace_folders` to allow indexed source folders to be specified
  explicitly. In monorepos, this allows the set of indexed folders to be restricted to a subset of
  the repository. #1627
- Rename configuration option `additional_workspace_folders` to `ls_additional_workspace_folders`
  and support the option across all language servers that use an InitializeParamsBuilder
  (previously limited strictly to the TypeScript server).
  Moved the option from SolidLSPSettings to LanguageServerConfig, where it belongs.

Apply InitializeParamsBuilder in TypeScriptLanguageServer and its subclasses.

test/conftest.py

@@ -66,6 +66,7 @@ def _create_ls(
     ignored_paths: list[str] | None = None,
     trace_lsp_communication: bool = False,
     ls_specific_settings: dict[Language, dict[str, Any]] | None = None,
+    workspace_folders: list[str] | None = None,
     additional_workspace_folders: list[str] | None = None,
     solidlsp_dir: Path | None = None,
 ) -> SolidLanguageServer:
@@ -79,6 +80,8 @@ def _create_ls(
         code_language=language,
         ignored_paths=ignored_paths,
         trace_lsp_communication=trace_lsp_communication,
+        workspace_folders=workspace_folders or ["."],
+        additional_workspace_folders=additional_workspace_folders or [],
     )
     effective_solidlsp_dir = solidlsp_dir if solidlsp_dir is not None else SerenaPaths().serena_user_home_dir
     project_data_path = os.path.join(repo_path, SERENA_MANAGED_DIR_NAME)
@@ -89,7 +92,6 @@ def _create_ls(
             solidlsp_dir=effective_solidlsp_dir,
             project_data_path=project_data_path,
             ls_specific_settings=ls_specific_settings or {},
-            additional_workspace_folders=additional_workspace_folders or [],
         ),
     )
 
@@ -101,11 +103,19 @@ def start_ls_context(
     ignored_paths: list[str] | None = None,
     trace_lsp_communication: bool = False,
     ls_specific_settings: dict[Language, dict[str, Any]] | None = None,
+    workspace_folders: list[str] | None = None,
     additional_workspace_folders: list[str] | None = None,
     solidlsp_dir: Path | None = None,
 ) -> Iterator[SolidLanguageServer]:
     ls = _create_ls(
-        language, repo_path, ignored_paths, trace_lsp_communication, ls_specific_settings, additional_workspace_folders, solidlsp_dir
+        language,
+        repo_path,
+        ignored_paths,
+        trace_lsp_communication,
+        ls_specific_settings,
+        workspace_folders,
+        additional_workspace_folders,
+        solidlsp_dir,
     )
     log.info(f"Starting language server for {language} {repo_path}")
     with ls.start_server_context():