All tests green

* Add newtype for moved type to preserve API compat

Enable Sync and Send for DynamicSender and DynamicReceiver.

DynamicSender and DynamicReceiver, just seem to be a fat pointer to a
Channel which is already protected by it's own Mutex already. In fact,
you can share the Channel already betwen threads and create Dynamic*er's
in the target threads. It should be safe to share the Dynamic*er's
directly. Can only be used when Mutex M of channel supoorts Sync.

Add support for peeking into the front of the channel if the value
implements Clone. This can be useful in single-receiver situations where
you don't want to remove the item from the queue until you've
successfully processed it.

Add stream impl for embassy-sync Channels