This patch:

1) Fixes a crash in KisTransactionBasedCommand. The check for first redo
   got lost somewhere during previous refactoring.

2) Fixes a deadlock in KisNode::prev/nextSibling(). The locks must be
   taken in a descending order only! Otherwise it'll result in a deadlock.
   See a comment in KisNode::prevChildImpl() function.

BUG:331708