Generation of valid JSON output for parseable output depends on being able to determine file types of inputs and outputs of compilation tasks. FileTypes.def defines multiple file kinds with multiple '.' extensions, such as '.abi.json' or '.features.json', but existing code attempted to compute file outputs only using the trailing suffix of the path after the last '.'. This led to some files not being recognized, which led to us not being able to generate valid JSON.
Resolves rdar://92961252
Introducing new entry-points that can be used from both Driver and Frontend clients, using an intermediary new type: `DetailedMessagePayload`, when needed.
