zdb: show BRT statistics and dump its contents

Same idea as the dedup stats, but for block cloning.

Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Kay Pedersen <mail@mkwg.de>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rob Norris <robn@despairlabs.com>
Closes #15541

tests/zfs-tests/tests/functional/cli_root/zdb/zdb_args_neg.ksh

@@ -58,7 +58,7 @@ set -A args "create" "add" "destroy" "import fakepool" \
     "setvprop" "blah blah" "-%" "--?" "-*" "-=" \
     "-a" "-f" "-g" "-j" "-n" "-o" "-p" "-p /tmp" \
     "-t" "-w" "-z" "-E" "-H" "-I" "-J" \
-    "-Q" "-R" "-T" "-W"
+    "-Q" "-R" "-W"
 
 log_assert "Execute zdb using invalid parameters."