Split server in smaller modules

src/include/watcher.hpp

@@ -0,0 +1,28 @@
+#pragma once
+
+#include <duckdb.hpp>
+#include <thread>
+
+namespace duckdb {
+namespace ui {
+struct CatalogState {
+  std::map<idx_t, optional_idx> db_to_catalog_version;
+};
+class HttpServer;
+class Watcher {
+public:
+  Watcher(HttpServer &server);
+
+  void Start();
+  void Stop();
+
+private:
+  void Watch();
+  unique_ptr<std::thread> thread;
+  std::mutex mutex;
+  std::condition_variable cv;
+  std::atomic<bool> should_run;
+  HttpServer &server;
+};
+} // namespace ui
+} // namespace duckdb