history: share outside of coordinator

[burgerdev]

This PR moves the history package into the common internal directory so that the SDK can make use of the definitions, in particular the Transition object. What I'm trying to enable is something like the following code for #1948:

func buildTransitionChain(manifests [][]byte) []*history.Transition {
	transitions := make([]*history.Transition, 0, len(manifests))
	lastTransitionHash := [history.HashSize]byte{}
	for _, m := range manifests {
		t := &history.Transition{
			PreviousTransitionHash: lastTransitionHash,
			ManifestHash: history.Digest(m),
		}
		transitions = append(transitions, t)
		lastTransitionHash = t.Digest()
	}
	return transitions
}