Update Oculus integration to 15.1

[Simon (Darkside) Jackson]

XRTK - Mixed Reality Toolkit Feature Request

Is your feature request related to a problem? Please describe

Oculus just updated their API/Unity asset to a .1 release. Would not usually trigger the need to update the API, however, the major note of this release is they added Oculus Quest 2 support.

[Dino Fejzagić]

@SimonDarksideJ I think this can be closed as you updated the Oculus plugin recently?

[Simon (Darkside) Jackson]

You're right Dino. Although there is probably another version out now ;)

[Stephen Hodgson]

I really wish they'd update to upm distribution