Further improve typings for 'unlock' functions

[mr-zwets]

now it gives type hints without the aliases for the different arguments, and gives all the union types which makes everything hard to read:

transfer: (functionParameters_0: string | Uint8Array<ArrayBufferLike> | SignatureTemplate) => Unlocker

spend: (functionParameters_0: string | Uint8Array<ArrayBufferLike>, functionParameters_1: string | Uint8Array<ArrayBufferLike> | SignatureTemplate) => Unlocker

where we would want something like:

transfer: (recipientSig: SignatureType) => Unlocker

spend: (pk: PubKeyType, sig: SignatureType) => Unlocker

[rkalis]

Additionally, for type inference in the Contract constructor, it probably makes sense to mark the constructor params as readonly, so that it would be possible to do something like this without running into TS errors:

const inputs = ['a', 'b', 'c'] as const;
const contract = new Contract(p2pkhArtifact, inputs);