Allow multiple substitute scripts

[axman6]

Currently we have several places where there's a one to one mapping between script hash and the substitute script that gets executed - Map ScriptHash Foo.

There's a few reasons a user might want to provide multiple scripts for each hash:

• When refactoring, ensuring results are the same
• When optimising , checking how CPU and memory usage compares.

So we probably want to move to supporting Map ScriptHash [Foo] where it makes sense. Currently the ConfigMap YAML file supports this, but then we convert it into a Map ScriptHash ScriptDetails