Stabilize text tests that grab windows.

Add window flags to make sure window stays on top to
tst_qquicktext::hAlignImplicitWidth() and
tst_qquicktextedit::hAlignVisual(). Add diagnostic output.
Determine the section size by checking the font size.
Add more characters to line 2 to make it more discriminative.

Task-number: QTBUG-32540
Change-Id: I19a74a775bf2663027ec211784870fd9f6547b48
Reviewed-by: Simo Fält <simo.falt@digia.com>
Reviewed-by: Alan Alpert <aalpert@blackberry.com>