Add API to cancel async jobs (#14602)

* Implement API to cancel async jobs

Co-authored-by: sfan5 <sfan5@live.de>

* update AsyncJob:cancel documentation from review

* Use IPC to unblock async

* review

* review async unblocking

* review

* Apply suggestions from code review

Co-authored-by: sfan5 <sfan5@live.de>

* minor licensing

---------

Co-authored-by: y5nw <y5nw@protonmail.com>
Co-authored-by: sfan5 <sfan5@live.de>

src/script/scripting_server.h

@@ -22,6 +22,7 @@ struct PackedValue;
 
 class ServerScripting:
 		virtual public ScriptApiBase,
+		public ScriptApiAsync,
 		public ScriptApiDetached,
 		public ScriptApiEntity,
 		public ScriptApiEnv,
@@ -41,14 +42,7 @@ public:
 	void saveGlobals();
 
 	// Initialize async engine, call this AFTER loading all mods
-	void initAsync();
-
-	// Global step handler to collect async results
-	void stepAsync();
-
-	// Pass job to async threads
-	u32 queueAsync(std::string &&serialized_func,
-		PackedValue *param, const std::string &mod_origin);
+	void initAsync() override;
 
 protected:
 	// from ScriptApiSecurity:
@@ -63,6 +57,4 @@ private:
 	void InitializeModApi(lua_State *L, int top);
 
 	static void InitializeAsync(lua_State *L, int top);
-
-	AsyncEngine asyncEngine;
 };