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.

modules/websocket/wsl_client.h

@@ -63,7 +63,7 @@ private:
 
 	String _key;
 	String _host;
-	uint16_t _port;
+	uint16_t _port = 0;
 	Array _ip_candidates;
 	Vector<String> _protocols;
 	bool _use_ssl = false;