A couple of QJSValue methods are missing

[gikari]

Summary

QJSValue is missing the following methods:

• call methods in case the QJSValue is a JS function (call, callAsConstructor, callWithInstance, isCallable).
• property methods (property by name/by index, set by name/by index, has, hasOwn, delete)
• is methods for various types:
  • isBool (feat(qmetaobject): add basic "is" wrappers for QJSValue #222)
  • isCallable
  • isDate
  • isError
  • isNull (feat(qmetaobject): add "is" wrappers for special QJSValues #224)
  • isNumber (feat(qmetaobject): add basic "is" wrappers for QJSValue #222)
  • isObject
  • isQMetaObject
  • isQObject
  • isRegExp
  • isString (feat(qmetaobject): add basic "is" wrappers for QJSValue #222)
  • isUndefined (feat(qmetaobject): add "is" wrappers for special QJSValues #224)
  • isVariant