Support for Non Standard Miniscripts

[sanket1729]

Miniscript language is designed to be standardness complete, however in certain applications like block explorer may require the ability to parse non-standard Miniscripts.

However, at this point, the current solution to change Miniscript ScriptContext from Generic Type to a parameter in every function seems overly invasive and is not worth the change as lose the strong type guarantees of Miniscript. (For example, using uncompressed keys in segwit context).

Considering the tradeoff that we maybe gaining very little compared by supporting non-standard miniscripts, and that there would be scripts on the blockchain that are not miniscripts which we would not be able to parse anyways, it is probably not worth it to support for those.

Marking this as brainstorming and a low priority issue for now. If there are additional usecases for converting Miniscript<MiniscriptKey, ScriptContext> to Miniscript<MiniscriptKey> we can consider implementing the changes.