InlineMessage: Fix showing close button

When there is a switch between incompatible anchors (like top and verticalCenter) depending on a condition, the previous anchor has to be reset before setting the new one.

Declarative bindings cannot assure this order of execution, so we need to go imperative even when it is a bit uglier.

The case to trigger this is not immediate (but it can happen). Here's the test case: inlinmessagetest.qml

Before	After