Merge pull request #12196 from opensourcerouting/xref-vtysh

*: rewrite `extract.pl` using `xref` infra

diff --cc bgpd/bgp_bmp.c
Simple merge

diff --cc bgpd/bgp_debug.c
Simple merge

diff --cc bgpd/bgp_evpn_vty.c
Simple merge

diff --cc bgpd/bgp_route.c
Simple merge

diff --cc bgpd/bgp_routemap.c
Simple merge

diff --cc bgpd/bgp_vty.c
Simple merge

diff --cc lib/if.c
Simple merge

diff --cc lib/routemap_cli.c
Simple merge

diff --cc ospf6d/ospf6_area.c
Simple merge

diff --cc ospf6d/ospf6_asbr.c
Simple merge

diff --cc ospf6d/ospf6_route.c
Simple merge

diff --cc ospfd/ospf_vty.c
Simple merge

diff --cc pathd/path_ted.c
Simple merge

diff --cc pimd/subdir.am
Simple merge

diff --cc zebra/interface.c
Simple merge