sync

Flush any pending document changes to the server.

Mirrors upstream @codemirror/lsp-client's LSPClient.sync(): it asks the workspace for the set of files with unsynced changes (Workspace.syncFiles) and emits a textDocument/didChange notification for each, honoring the negotiated DocumentSyncMode. Calls are serialized so notifications go out in version order.

No-op when the client has not been initialized yet.