todo deleted
IDEA-128955 Push dialog: focus should be in the main area by default

* Tree become preferred focus component;
* first checked repository node in lexicographical order selected by default;
* need to update ui repositories order, see todo
IDEA-129008 PushDialog: create PushSpec  only for @NotNull PushTarget, and add annotations.

* nullable target could be only in MyRepoModel,in any other places PushTarget should be @NotNull;
* generics updated, need to improve