e.g. sh(addr(ADDR)) or sh(raw(HEX)) are invalid descriptors.
Making sh and wsh top level functions to return addr/raw descriptors when
the subscript inference fails.
Added the additional elements output types of "true" and "fee" to the
decodescript lambdas, we should confirm that this is correct for the fee
outputs. ie. that it is acceptable to permit fee outputs to be wrapped
The descriptor inference logic would previously always use a dummy
signing provider and would never analyze the witness script of a P2WSH
scriptPubKey.
Note even a valid Miniscript might not always be decodable from Script
without more contextual information (for instance the key preimage for a
pk_h).
