Merge pull request #62036 from apple/egorzhdan/cxx-explicit-iterator

[cxx-interop] Specify `Iterator` explicitly for `CxxRandomAccessCollection`

Author: egorzhdan

stdlib/public/Cxx/CxxRandomAccessCollection.swift

@@ -30,6 +30,7 @@ extension UnsafeMutablePointer: UnsafeCxxRandomAccessIterator {}
 
 public protocol CxxRandomAccessCollection: CxxSequence, RandomAccessCollection {
   override associatedtype RawIterator: UnsafeCxxRandomAccessIterator
+  override associatedtype Iterator = CxxIterator<Self>
   override associatedtype Element = RawIterator.Pointee
   override associatedtype Index = Int
   override associatedtype Indices = Range<Int>