zebra: separate zebra_vrf_lookup_table_with_id()

zebra: separate zebra_vrf_lookup_table_with_id()

We were creating `other` tables in rib_del(), vty commands, and
dataplane return callback via the zebra_vrf_table_with_table_id()
API.

Seperate the API into only a lookup, never create
and added another with `get` in the name (following the standard
we use in other table APIs).

Then changed the rib_del(), rib_find_rn_from_ctx(), and show route
summary vty command to use the lookup API instead.

This was found via a crash where two different vrfs though they owned
the table. On delete, one free'd all the nodes, and then the other tried
to use them. It required specific timing of a VRF existing, going away,
and coming back again to cause the crash.

=23464== Invalid read of size 8
==23464==    at 0x179EA4: rib_dest_from_rnode (rib.h:433)
==23464==    by 0x17ACB1: zebra_vrf_delete (zebra_vrf.c:253)
==23464==    by 0x48F3D45: vrf_delete (vrf.c:243)
==23464==    by 0x48F4468: vrf_terminate (vrf.c:532)
==23464==    by 0x13D8C5: sigint (main.c:172)
==23464==    by 0x48DD25C: quagga_sigevent_process (sigevent.c:105)
==23464==    by 0x48F0502: thread_fetch (thread.c:1417)
==23464==    by 0x48AC82B: frr_run (libfrr.c:1023)
==23464==    by 0x13DD02: main (main.c:483)
==23464==  Address 0x5152788 is 104 bytes inside a block of size 112 free'd
==23464==    at 0x48369AB: free (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)
==23464==    by 0x48B25B8: qfree (memory.c:129)
==23464==    by 0x48EA335: route_node_destroy (table.c:500)
==23464==    by 0x48E967F: route_node_free (table.c:90)
==23464==    by 0x48E9742: route_table_free (table.c:124)
==23464==    by 0x48E9599: route_table_finish (table.c:60)
==23464==    by 0x170CEA: zebra_router_free_table (zebra_router.c:165)
==23464==    by 0x170DB4: zebra_router_release_table (zebra_router.c:188)
==23464==    by 0x17AAD2: zebra_vrf_disable (zebra_vrf.c:222)
==23464==    by 0x48F3F0C: vrf_disable (vrf.c:313)
==23464==    by 0x48F3CCF: vrf_delete (vrf.c:223)
==23464==    by 0x48F4468: vrf_terminate (vrf.c:532)
==23464==  Block was alloc'd at
==23464==    at 0x4837B65: calloc (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)
==23464==    by 0x48B24A2: qcalloc (memory.c:110)
==23464==    by 0x48EA2FE: route_node_create (table.c:488)
==23464==    by 0x48E95C7: route_node_new (table.c:66)
==23464==    by 0x48E95E5: route_node_set (table.c:75)
==23464==    by 0x48E9EA9: route_node_get (table.c:326)
==23464==    by 0x48E1EDB: srcdest_rnode_get (srcdest_table.c:244)
==23464==    by 0x16EA4B: rib_add_multipath (zebra_rib.c:2730)
==23464==    by 0x1A5310: zread_route_add (zapi_msg.c:1592)
==23464==    by 0x1A7B8E: zserv_handle_commands (zapi_msg.c:2579)
==23464==    by 0x19D689: zserv_process_messages (zserv.c:523)
==23464==    by 0x48F09F8: thread_call (thread.c:1599)

Signed-off-by: Stephen Worley <sworley@cumulusnetworks.com>