Javascript debugging should not be enabled for chakra backend on HoloLens

[chrisfromwork]

We've determined that chakra script debugging does not work on hololens. This causes AppRuntimeChakra.cpp to throw an exception when kicking off a debug babylon native build on a HoloLens device due to a call to JsStartDebugging.

Workarounds include commenting out this line of code or building for release. But, in delivering a high quality developer experience, we should prevent this crash for debug builds on HoloLens. Third party developers shouldn't need to comment out code in BabylonNative releases to get HoloLens debug images to work.

[tymlipari]

Worth noting that the reason this crashes is due to the fact that VS isn't correctly deploying the JS debugging support along with the remote debugger package. We've pinged them about this, but we should figure out if we can gracefully fall back when it's not present while we wait for a fix.

[tymlipari]

Since it looks like we're unlikely to get Chakra debugging support for ARM targets, the remaining work to enable a Babylon Native debugging story on HoloLens 2 is tracked by #463 and #464.