fix(ios): Use anti-aliasing for accurate borders

[CatchABus]

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What is the current behavior?

There are cases when iOS views display extra borders. That is because border layers/masks have no anti-aliasing.

What is the new behavior?

iOS view borders will draw properly using anti-aliasing on corresponding layers.
This is a replacement for PR #10600. Previous attempt was a hackish solution and it eventually caused new problems (thanks @rigor789 for letting me know)

Fixes/Closes #10548.