[INTERNAL] lib/processors/jsdoc: support optional methods also in classes

So far, the documentation build only allowed optional methods in
interfaces. But UI5 in several places specifies methods on a base class
level without implementing them. Subclasses can then implement such a
method to get a certain behavior (example: Control#getAccessibilityInfo).

TypeScript (meanwhile?) allows to describe this as optional methods in
the base class.

To allow to use this and thereby to better describe those methods in
the TypeScript types, the JSDoc template lifts its limitation and writes
out the 'optional' marker also for methods in classes.

Note: this is now even possible for static class methods, although this
is not used yet in the framework.

Cherry-picked from SAP/openui5@a7ccde144.

Author: codeworrior

lib/processors/jsdoc/lib/ui5/template/publish.cjs

@@ -2308,7 +2308,7 @@ function createAPIJSON4Symbol(symbol, omitDefaults) {
 		if ( symbol.__ui5.stereotype !== 'xmlmacro' && ownMethods.length > 0 ) {
 			collection("methods");
 			ownMethods.forEach(function(member) {
-				writeMethod(member, undefined, symbol.kind === 'interface');
+				writeMethod(member, undefined, symbol.kind === 'interface' || symbol.kind === 'class');
 				if ( member.__ui5.members ) {
 					// HACK: export nested static functions as siblings of the current function
 					// A correct representation has to be discussed with the SDK / WebIDE