add support for tabular display of IEnumerable<T>

[jonsequitur]

Proposal: Add a DisplayTable extension method for IEnumerable<T> that will produce a tabular display instead of a treeview-style display.

A number of people have asked for the older table formatter to be made available again for sequences.

#3081
#3085

In #3081 I proposed a workaround by first calling ToTabularDataResource, which has a custom formatter that provides a tabular output:

The ergonomics could be improved though.

In this comment, @scottstephens made a suggestion for an API that would sit alongside Display and not require a separate using using directive. This will make it more discoverable and decouple it from the TabularDataResource details, which are intended more for serialization than display.