Retrieve default properties for Plugins

When creating a plugin using the "Simple" tab, it is using/setting the properties as specified in the "properties" section of the json MANIFEST file, and things work as as expected.

However, when creating a plugin using the "Advanced tab", it is just proposing different defaults and completely ignoring the settings dictated by the plugin developer in the "properties" section of the json MANIFEST file. This used to work properly before; I'm not sure if this issue was introduced with 11.2-U5 or before that. 

The way it should work IMHO, is that the manifest file is read and these settings are proposed as the defaults in the "Advanced screen", instead of proposing different settings between the "simple" and "advanced" screens and keep the users guessing.

One could even go a step further and make the settings provided (dictated?) by the plugin developer in the plugin manifest as read-only in the FreeNAS UI.

As an example the MineOS plugin: The properties in the MANIFEST json file

Using the "Simple screen" it behaves a expected, but the "Advanced screen" doesn't set the "mount_linprocfs" and "mount_procfs" flags.

Another example is the Plex plugin.  That plugin requires VNET=on.  This ised to be set in the MANIFEST but that setting was removed at one point, adding to the confusion.