Have different grouping options for the agent report

[rich-iannone]

The agent report currently has a few rudimentary options for filtering/arranging validation steps by failure condition. However it would be great to take this a step further and include options for grouping validation steps. The grouping can be made across validation types (row-based, column-based, whole table, etc.), and also by the columns themselves (groups for each column).

For validation plans with lots of steps, this last method of grouping will make the reporting much easier to parse and to locate the results of interest.