[Feat][Grid] Allows passing null to indicate empty value to state properties

[kirchoni]

For state properties like sort,filter,select etc. the Grid accepts either a Descriptor or undefined - However the undefined` value falls back to the internal state's value, which makes reseting the grid's state to "nothing" a bit more vaguely then we want to. For example, to reset the filter, one must set it's "default" value which actually is:

setFilter({ logic: 'and', filters: [] })

We would like to explore the possibility to pass null which would keep the component in it's controlled-state but still allows easier way to reset it's value.

This would affect the following properties:

• filter
• sort
• skip/take
• group
• detailExpand
• groupExpand
• select
• edit