Support for watchpack options

[no-mae]

Support for watchpack options.
I'll set it to { poll: true } to run hot reload in my env.

[EndilWayfare]

This is a fantastic addition! I was about to submit a pull request of my own that just forwarded the watchOptions on the compiler itself, if set, because they weren't otherwise user set-able.

I like this solution better, because it's more thorough and configurable. I would suggest, though, defaulting to the compiler's watchOptions for options not set on the plugin, so the user's project-wide watch settings are DRY unless manually necessary.