Support remote grouping

[chuckn0rris]

We need to add support grouping (group feature) for remote store, or update docs with info that we do not support it.

Forum post

go here and check if grouping is working.
https://www.bryntum.com/examples/grid/paged/

[ExtAnimal]

This would entail prepending the grouper to the front of the sorters sent to the server to determine data order.

Then the server would have to attach some metadata to the JSON return packed which would be another property in addition to the data, success and total properties in the packet.

Perhaps

groups : {
    "group1Key": 5,
    "group2Key": 100
}

Which would describe the groups contained by the data object. So that the grouping would know that if the page size was 20, that "group1Key" group ends and should have a group footer special record inserted after it, but "group2Key" is not at its end and should have no group footer record. or maybe it should have the full group footer with the correct, aggregated group data. Somehow. Setting all this up in the store would be very complex.

Obviously, collapsing would not be available. It would be pointless. The would be no extra data to move up into view.

All in all, this would be two weeks of work, for a very stilted, limited UI which hides a lot of data and isn't very useful.