Remove "bind -k" terminfo key names, update "bind --key-names"

I don't think there's a relevant terminal where the "bind -k" notation is
still needed. The remaining reason to keep it is backwards compatibility.

But "bind -k" is already subtly broken on terminals that implement either
of modifyOtherKeys, application keypad mode or the kitty keyboard protocol,
since those alter the byte sequences (see #11278).

Having it randomly not work might do more harm than good. Remove it.

This is meant go into 4.1, which means that users who switch back and forth
between 4.1 and 4.0 can already use the new notation.

If someone wants to use the bind config for a wider range of versions they
could use "bind -k 2>/dev/null" etc.

While at it, use the new key names in "bind --key-names", and sort it like
we do in "bind --function-names".

Closes #11342

tests/checks/bind.fish

@@ -141,6 +141,9 @@ bind tab
 bind ctrl-\b
 # CHECKERR: bind: Cannot add control modifier to control character 'ctrl-h'
 
+bind -k nul 'echo foo'
+# CHECKERR: bind: the -k/--key syntax is no longer supported. See `bind --help` and `bind --key-names`
+
 # Either Return or ctrl-m.
 bind \r
 # CHECK: bind --preset enter execute