Refactor duplicated logic in http/ipc servers.

[njgheorghita]

https://github.com/carver/trin/pull/2/files#r590773236

Oof, there's a lot of duplicated logic in here between the two servers. Not sure the best way to DRY off-hand. Maybe make a function that takes in the json iterator and returns an iterator over the result values.

Also improve input data validation

I know the error handling was already this way in the IPC code, but it's bad news. Sending bad input data to trin should reply with an error, instead of crashing trin.

https://github.com/carver/trin/pull/2/files#diff-b2812f19576dd53d0c35b107a322f58a00fce6977f4b5976e1961853982af3ccR199-R203