Implemented SVY-6997 : Refactor tabindex type; move code in property
type as much as possible

Actually that meant removing old server side based impl. and adding it
all on the client. This way there's less custom code all over the place
on server, the client side directive can be used to completely control
tabIndexes, even in non-servoy components and also it is each container
like component that controls it's behavior (tab panel, split pane,
portal, ...) - so that works for any custom component as well.

Also some resources load moves now from server to clients.