Is your feature request related to a problem? Please describe.
The timeout and killSignal options are available in execFile[Sync](), exec[Sync](), spawnSync() but not in spawn() nor fork().

Those methods could be useful for spawn() and fork() too. For example, projects like execa (by @sindresorhus) use userland code to bring those options to spawn().

Describe the solution you'd like
Add those options to spawn() and fork().