fix insetting of scene view

[jurvis]

Checklist

• I've tested my changes.
• I've read the Contribution Guidelines.
• I've updated the documentation if necessary.

Motivation and Context

When setting ShinyView to the frame of device, a strange inset is present on iPad:

Ran my fix on the iPad simulator which did end up rendering fine + example app still works:

Description

removed the setting of scene view's frame from it's initialiser and do it in ShinyView's layoutSubviews instead

[jurvis]

sample project demonstrating the bug: https://we.tl/t-YDC6mJDQf2

[efremidze]

You are also removing the inset. The inset is necessary for the example.