Add TypedArray API using Heap-wrapped objects

[Xanewok]

Needed for https://github.com/servo/servo/pull/20267.

This changes TypedArray wrapper type to only contain typed array-related logic and not handle rooting, and introduces 2 different possible storage options for wrapped objects

• *mut JSObject, can be rooted on stack (e.g. using CustomAutoRooter)
• Box<Heap<*mut JSObject>>, can be rooted on heap with JSTraceable trait (implemented on Servo side)

Since the API changes are breaking, I bumped minor version so that Servo will not break when updating.

r? @jdm

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This change is 

[jdm]

@bors-servo r+ Thanks for working on this!

[bors-servo]

:pushpin: Commit eef813b has been approved by jdm

[bors-servo]

:hourglass: Testing commit eef813b56e87de569e2ec9947b7731d01c90afd6 with merge d2a3ed64efdc6e422d22f9f18fa6253e3f063b58...

[bors-servo]

:sunny: Test successful - status-appveyor, status-travis Approved by: jdm Pushing d2a3ed64efdc6e422d22f9f18fa6253e3f063b58 to master...