InputView: attach property array to parent property set only on deman

[ashklianko]

Problem:
When InputView is executing layout/update it always creates PropertyArray if it doesn't exist, and then immediately attaches it to the parent property set. This immedialtely makes 'layouted' property set differ from persisted one and requires extra efforts to calculate if data has really changed or not.

Solution:

1. If property array for InputView is missing in the parent property set then create it but don't attach to parent
2. When data in this newly created property array added/modified then attach it to the parent prop set
3. When new property array has no data then detach it. When existing non empty prop array becomes empty also detach it so it is removed on save

Potential issues to deal with:
-order of arrays in the parent's prop set
-default values in arrays