Fix migration script to wrap symmetric-key in key-type container

The migration script was incorrectly placing symmetric-key directly
under the symmetric-key node, but according to the YANG schema, it
should be wrapped in a key-type container. This fixes the libyang
error: "Node 'cleartext-key' not found as a child of 'symmetric-key'
node" when migrating from v1.5 to v1.7.

Co-authored-by: troglobit <183517+troglobit@users.noreply.github.com>

src/confd/share/migrate/1.7/20-keystore-cleartext-key-rename.sh

@@ -1,5 +1,5 @@
 #!/bin/sh
-# Rename cleartext-key to symmetric-key
+# Rename cleartext-key to symmetric-key and wrap in key-type container
 
 file=$1
 temp=${file}.tmp
@@ -8,10 +8,12 @@ jq '
 if .["ietf-keystore:keystore"]?."symmetric-keys"?."symmetric-key" then
   .["ietf-keystore:keystore"]."symmetric-keys"."symmetric-key" |= map(
     if ."infix-keystore:cleartext-key" then
-      # Rename cleartext-key to symmetric-key
+      # Rename cleartext-key to symmetric-key and wrap in key-type
       ."infix-keystore:cleartext-key" as $key_value |
       del(."infix-keystore:cleartext-key") | . + {
-        "infix-keystore:symmetric-key": $key_value
+        "key-type": {
+          "infix-keystore:symmetric-key": $key_value
+        }
       }
     else
       .