Options to enable/disable arrays from tuple types

Currently Typechains generates output types that are an intersection (`&`) between an array and an object, like so:

```( [string, string] & { prop1: String, prop2: string } )```

We find that this makes autocomplete very tricky when coding and also occasionally causes typing issues - I wonder what the reasoning behind this output format is, and whether there is any appetite for a flag/option to turn this off?

(Ditto the output filename - I see it was recently changed from `.d.ts` to `.ts`)