global-functions: $ParseKeyValueStore: support JSON as input

This used to require a key=value store, separated with commas. An
example for `netwatch-notify` is:

    /tool/netwatch/add comment="notify, name=example.com" host=93.184.215.14;

Now JSON is supported as well, so you could use:

    /tool/netwatch/add comment="{\"notify\":true,\"name\":\"example.com\"}" host=93.184.215.14;

Looks more clumsy here, but may be of help in more complex setups...

global-functions.rsc

@@ -919,6 +919,13 @@
 # parse key value store
 :set ParseKeyValueStore do={
   :local Source $1;
+
+  :if ([ :pick $Source 0 1 ] = "{") do={
+    :do {
+      :return [ :deserialize from=json $Source ];
+    } on-error={ }
+  }
+
   :if ([ :typeof $Source ] != "array") do={
     :set Source [ :tostr $1 ];
   }