Wrong type annotations in pyk

[pxhdev]

In pyk.kcfg.kcfg.py, the create_ndbranch function says that the key of KCFG._ndbranches should be of type KCFG.NDBranch. However, it is mistakenly annotated as NDBranch, which actually points to class NDBranch(KCFGExtendResult). There are lots of wrong annotations like this in that file and as a result I get lots of error from lsp.