Implement WireDispatcher

We have several cases where we need a simple `InputWire` that dispatches the incoming data to multiple instances of `OutputWire`. We use a `WireTransformer` with an `identity()` transformation, which works, but is inefficient. A specialized implementation will be much simpler and faster.

Locate the existing InputWire, OutputWire, and WireTransformer abstractions, then inspect the identity() transformation and its call sites to understand the current dispatch path. The work is done when a specialized WireDispatcher provides the same fan-out behavior without relying on the inefficient identity transformation.

Written by the indexing model from the issue text.