Java2Swift: Generalize conformances of Java collection types to Swift sequence protocols

The `JavaKitCollection` module has a [conformance](https://github.com/swiftlang/swift-java/blob/main/Sources/JavaKitCollection/List%2BSequence.swift) of `java.util.List` to Swift's `Sequence` protocol. We should find a way to expand and generalize this so all of the various Java collection types can be treated as Swift sequences.