Specify iOS simulator runtime version (#22474)
- Allow specification of iOS simulator runtime version to use.
- Pick simulator runtime version (iphonesimulator 16.4) that is supported by the Xcode version (14.3.1) that we use.
- Disable CoreML EP's DepthToSpace op support for CoreML version less than 7, with DCR mode, and FP16 input. It doesn't produce the correct output in this case.
- Some cleanup of iOS test infrastructure.
