[psteinroe]

Stacked on #902 → #895 → #881. Must merge after #881.

The configuration watcher was registered for rootUri only (C5), as <rootUri>/**/postgres-language-server.jsonc with the path pasted into the glob unescaped. In a multi-root workspace, or for a folder added later through didChangeWorkspaceFolders, creating, editing or deleting a configuration file was never picked up, and a client that sends workspaceFolders but no rootUri got no watcher at all. The user configuration (#878) and extends targets weren't watched either, and nothing told the user that the user configuration was being applied (C16).

What changed

• One watcher per workspace folder (or the root URI when there are no folders): RelativePattern { baseUri: <folder>, pattern: "**/postgres-language-server.jsonc" } when the client announces relativePatternSupport, else a string glob with the path escaped (*?[{} in brackets, / as separator on Windows). They are registered again after every reload, so added and removed folders are covered.
• Also watched: the configuration file above a workspace folder that applies to it, the explicit configurationPath, the user configuration paths (also before one exists), and every file a loaded root or nested configuration extends. A change of any of them goes through the debounced reload from perf(workspace): bound nested configuration discovery #895. When a configuration fails to load, the files it extended before stay watched, so fixing it is picked up.
• Announcement: when the user configuration applies, the LSP logs Using the user configuration at <path> for <folder>, which has no configuration file. (INFO window/logMessage) and the CLI prints Using the user configuration at <path> to stderr, so it stays out of --reporter json and format --stdin-file-path output.
• apply_extends now returns the files it extended, and LoadedConfiguration carries them plus is_user_configuration.

Tests

• LSP the_configuration_files_of_every_workspace_folder_are_watched: no rootUri, two folders, both with and without relativePatternSupport; after adding three and removing one, the new registration covers three and not one.
• LSP a_change_of_an_extended_file_reloads_the_configuration: editing ../shared/base.jsonc outside the workspace folder changes the severity of an open document.
• LSP the_user_configuration_and_extended_files_are_watched: the registration lists both.
• CLI check_announces_the_user_configuration (Unix, via XDG_CONFIG_HOME): the line is on stderr, not in the JSON report.

Not covered

• Only ] is left unescaped in string globs; LSP glob syntax has no escape for it, and a lone ] is literal.
• A missing extends target can't be watched, because the load fails before it is known; the configuration file itself still is.