[Binding] ForEach view

[chkn]

• Bridge IList<> to Swift as RandomAccessCollection

• Bind ForEach view. Now we can expose IList<> instead of RandomAccessCollection, but we might still need to bind and expose a couple other types, such as Range and the Identifiable protocol.

• [C#] In the source generator, add support for emitting a ForEach view when a C# foreach statement is encountered in a ViewBuilder that enumerates an IList<>, or when a for statement is encountered stepping by 1 over integers. If it doesn't conform to those requirements, then a helpful diagnostic should be emitted.

• [F#] The computation expression should implement the For method, restricting the first argument to types that implement IList<>. There doesn't appear to be a nice way to handle ranges. (depends on [F#] Create computation expressions for ViewBuilder #24)