add helper functions moveToCenterOfElement and moveToCenterOfBounds

[Illyism]

const DOMElemRef = document.querySelector('.some-element')
moveToCenterOfElement(DOMElemRef) // moves viewport to the center of this element

const elemBounds = document.querySelector('.some-element').getBoundingClientRect()
moveToCenterOfBounds(elemBounds) // moves viewport to the center of this bounding box

moveToCenterOfBounds is useful to have separately so you can pass just the bounding box around. Or make your own one without having to use HTML, eg moveToCenterOfBounds({ left: 0, top: 0, width: 100, height: 100 })

[savtwo]

@anvaka This is very helpful. Any chance it can be merged?