feat(tables): show whether abstract table is table or view (or materialized, etc...)

[gforsyth]

I was thinking about #9199 and led myself down a rabbit hole.

In that issue, we discussed making sure that all backends create views when doing a read_* so they don't clobber existing data.

Then if the user wants to re-use an existing name, they can first drop the existing table object using drop_table or drop_view.

One hiccup there, how do they know whether it's a table or a view? Chances are, they don't, especially if we created it for them.

Given that, should we rethink the output of list_tables (and the TablesAccessor) to include information about what kind of abstract table a given object is?

This dovetails with the work on the DDL accessor thing, but we also can't expect users to know to look in con.ddl.list_views() to check if the existing name is there or not.

What if we fancy up the output of con.tables to also indicate whether a given object is a table or a view (or other) ?

[gforsyth]

An alternative that came up in a separate discussion:

Have a generic drop method that takes table objects (not a stringified name), so if we give it a view, it calls drop_view, etc... Currently, the base Table object doesn't include this information, so we'd also need to add that metadata to the table objects.

If we go with the pattern I suggested above, it will be much easier to manage after the DDL accessor work is in, since we'll already be calling out to specific table- and view-listing.