[Task] Add pimcore 10 and 11 support for new menu creation

[mattamon]

Changes in this pull request

Resolves #403

Additional info

If new preMenuBuild Event is available use the new methods, if not use the pimcoreReady Event to setup the menu

[kingjia90]

I am wondering if we could futher break down and extract menu items to avoid duplicate fragments, at the moment initToolbar and initMenu are quite similar.
https://www.diffchecker.com/ItcLvg3w/

What i want to avoid is that whenever one change something, would always have to apply changes to the other method, but at the same time, it mustn't limit 11 potential improvemenents.

[mattamon]

I'm going to take a look into that. I think the main part is how the menu is added, so I could basically make proper functions to get the menus and then in initToolbar add them the old way and in initMenu, use the new approach.

[mattamon]

I restructured it like I said above. It is still not the nicest way, but much better than before. I think changing it more, would only make it more complicated.

[kingjia90]

Looks much better but currently the items in initMenu do not make the most of the priority field (adding this property, shouldn't affect the old approach) and wondering if it would be worth to change from

let somevar = somefunc;
if (somevar){
   array.push(somevar);
}

to just array.push(somefunc); and clean the null values (since they can return null) at the end of the function or just before menu.cmf

[mattamon]

Since it is it's own menu, and we do not set the priority anywhere, the priority gets set automatically. I would change this approach tbh because the result would be the same as before, right?

Just pushing the function seems legit, but we would have a problem with the customerMenu, itself. If there are no changes for the submenu, then pushing the function is okay, but I would rather go for the a consistent approach. Wdyt?