Style: Partially apply clang-tidy's cppcoreguidelines-pro-type-member-init

Didn't commit all the changes where it wants to initialize a struct
with `{}`. Should be reviewed in a separate PR.

Option `IgnoreArrays` enabled for now to be conservative, can be
disabled to see if it proposes more useful changes.

Also fixed manually a handful of other missing initializations / moved
some from constructors.

editor/fileserver/editor_file_server.h

@@ -63,12 +63,12 @@ class EditorFileServer : public Object {
 	Mutex wait_mutex;
 	Thread thread;
 	static void _thread_start(void *);
-	bool quit;
-	Command cmd;
+	bool quit = false;
+	Command cmd = CMD_NONE;
 
 	String password;
-	int port;
-	bool active;
+	int port = 0;
+	bool active = false;
 
 public:
 	void start();