Hugr Type Lowering

[acl-cqc]

• Replace one type with another - a bit like a Substitution but for fixed (maybe only Extension) types not type variables
• If the source type is copyable but the destination type is linear, insert some (specified) dup and free ops
• For parameterized ops (Extension Ops or those in hugr-core), just replacing in the "type args" should do it
• But, for extension ops that input or output values of the replaced type (not via type parametrization), also need to replace ops