db-ctl-base: Always support all tables in schema.

When one adds a new table to a database schema, it's easy to forget to
add the table to the list of tables in the *ctl.c program.  When this
happens, the database commands for that program don't work on that table
at all, even for commands like "list" and "create" that don't need any
special help.  This patch fixes that problem, by making sure that
db-ctl-base always has the complete list of tables.

Previously, each ctl_table_class pointed directly to the corresponding
ovsdb_idl_table_class.  With this patch, there are instead two parallel
arrays, one of ovsdb_idl_table_classes and the other of ctl_table_classes.
This change accounts for the bulk of the change to the db-ctl-base code.

Signed-off-by: Ben Pfaff <[email protected]>
Acked-by: Lance Richardson <[email protected]>