QOL improvements, easier setup, fix for Vive controllers

If you're migrating from an older version of this prefab, make sure to read the new installation steps, especially if you're using the VRCPickup component.

The installation is a lot easier now, just use one of the template panel provided in the MyroP/PortablePanel folder.

Patch note :

• Fixed an issue related to Vive controllers, Vive players can now more easily interact with the panel. (Before, using the trigger button would trigger the "Grab" event, so it happened that Vive players would accidentally scale the panel while trying to interact with it)
• Renamed the Grabbable parameter to Is Pickupable, this bool value is now private, but can be externally toggled with the SetPickupable() function, setting that boolean to false also makes VRCPickups not grabbable anymore, so it should be set to "On" in most cases.
• While scaling down the panel, the panel now closes if the distance between both hands is below 15cm, that value is stored in a new const variable CLOSING_HAND_DISTANCE
• Panels that respawned can now be grabbed, and thrown away again, which will trigger the "disintegration" effect.