UE-78077 Editor will not load after enabling WMR plugin - "Failed to preload WindowsMixedRealityHMD.dll"

-Need WMR to always require the HololensAR plugin, not only on hololens because there is a dependency there on both platforms.
-HololensAR plugin will now be automatically enabled when WMR is enabled.
#rb joe.conley
#jira UE-78077

#ROBOMERGE-SOURCE: CL 7663218 in //UE4/Release-4.23/...
#ROBOMERGE-BOT: RELEASE (Release-4.23 -> Main) (v372-7473910)

[CL 7663220 by jeff fisher in Main branch]

Engine/Plugins/Runtime/WindowsMixedReality/WindowsMixedReality.uplugin

@@ -95,6 +95,7 @@
 			"Name": "HoloLensAR",
 			"Enabled": true,
 			"WhitelistPlatforms": [
+				"Win64",
 				"HoloLens"
 			]
 		}