PY-17392 Update specific PSI elements, instead of entire parameter and statement...

PY-17392 Update specific PSI elements, instead of entire parameter and statement lists in the quickfix

Helper method PyUtil#addElementToStatementList moves old statement list
on the next line (below the header of the parent statement), if
necessary, *before* the new statement is inserted. If it's done
afterwards and new statement is multiline, it might not be properly
indented.