feat(ip): Create function to get link types

Create _comp_cmd_ip__link_types function that gets all the link types
supported by the ip command

Co-Authored-By: Koichi Murase <myoga.murase@gmail.com>

completions/ip

@@ -15,6 +15,19 @@ _comp_cmd_ip__netns()
     )"
 }
 
+_comp_cmd_ip__link_types()
+{
+    _comp_compgen_split -- "$(
+        {
+            ${1-ip} -c=never link help || ${1-ip} link help
+        } 2>&1 | command sed -e \
+            '/TYPE := /,/}/!d' -e \
+            's/.*{//' -e \
+            's/}.*//' -e \
+            's/|/ /g'
+    )"
+}
+
 _comp_cmd_ip()
 {
     local cur prev words cword comp_args