AbstractCard rework

• Changes

  • parent items visible when their child exists and is visible.
  • strict column and row setters, do not let qt automaticaly position items inside the GridLayout and manually set column and row properties
  • min and max height limitations
  • update doc

• BUG fixes (encountered bugs)

  • parent item's child visibility is not updated, FIXED: remove check if parent's item child is visible and check only if it exists.
  • remove strict column and row setters (because of previous bug)

MR DEP: !590 (closed)

Copy paste this file into master branch controls/templates folder see the results in kirigami-gallery (first bug encounter I listed). AbstractCard.qml