add feature to use grab binding to drag and drop values and object in the inspector

[zodiepupper]

not sure the specific implementation detail required for this.

the requested behavior is basically that of Resonite/Neos. essentially drag and drop but adapted into the VR context.

when the user activates the grip/grab binding while hovering certain types of fields in the inspector (or presumably any ui) it should put that grab manager into a mode where it is "holding" the value and then releasing drops the value into whatever field is being hovered upon release.

it may be a good idea to implement this at the level of the 3dPanel addon so that it's generalized for all ui panels.

[zodiepupper]

my new thoughts are that it would need to be a change to interactionray and the 3dpanels. if 3dpanles can handle a special event that is the grab event then it could find the element under the cursor and try to dynamically place that value into a holder on the interactionray and when dropped does the inverse if the field is writeable

[zodiepupper]

so, the ideal way to do this is to make it a type of input event that gets sent to the current panel the user is pointing at.

what i mean is that we should make the Panel3Ds behave with the same methods as all the other objects. inspectors should be regular objects and objects should be able to intercept the grab bind in some situations.