Add a tool that runs the heuristic for context properties and dumps the
.ini generated by the heuristic search, for future calls of qmllint.
Add a test.
Task-number: QTBUG-128232
Change-Id: I5d03db45f41ef90c6f5d931837aaa466abc33303
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>