Pretend to be a TTY

Some tools produce different output when they detect that terminal is not a TTY (interactive). For example, TypeScript produces colorized output by default only in TTY mode. Otherwise the `--pretty` flag must be specified to force colorized output.

When a process is run via Wireit, the process will think it is not attached to a TTY, because we use the default `pipe` setting to handle stdio from `spawn` (https://nodejs.org/api/child_process.html#optionsstdio), so it isn't attached to a TTY directly. We could instead use `inherit`, but that would not allow us to capture the output, which we need for storing stdio replays.

A downside of this is that it does not match the standard behavior of `npm run`, which uses `inherit`. Matching the behavior of npm is one of our goals.

Using a library like https://github.com/microsoft/node-pty may be the only way to trick processes into thinking they are attached to a TTY, while also being able to capture the output for the replay files. We should do a little more research to confirm this, as there is a chance there is a simpler solution. This library is somewhat large, includes a native library, and has a different interface to `spawn`. Note we would only want to do this when we detect _we_ are running in a TTY.