Set plugin event priority

[hugopeek]

Currently you can only define an array of event names in the config, but the plugin_events table allows you to also set a priority and propertyset for each event.

They are both hardcoded now to 0, but for the rare occasions where you'd need to change that, this update adds the option to define each event as a separate JSON object in the config:

{
    "package":{
        "elements": {
            "plugins": [{
                "name": "PackagePlugin",
                "events": [
                    {
                        "event": "OnDocFormSave",
                        "priority": 10
                    },{
                        "event": "OnWebPagePrerender",
                        "propertyset": 5
                    }
                ]
            }]
        }
    }
}

It will still fall back to 0 if you don't provide a propertyset or priority, and the current format of only entering an array of event names also still works.

[hugopeek]

This also answers #127 btw..

[theboxer]

Referencing property set in a config by an ID is a no-go. IDs change.

[hugopeek]

You're right, referencing property set by ID is a bad idea. The thing is: it's being reset to default (0) each time you update the package. So there's currently no way to use a custom set, without reassigning it after every update.

I removed the property set feature in this PR and will try to create a separate PR for the reset issue. So this PR is now purely about updating even priority.

[sebastian-marinescu]

Nice feature, thanks @hugopeek
Will come in handy! ❤️