Support resolve.alias in webpack config

[vadimdemedes]

I'm currently working in a huge codebase, where authors use resolve.alias to avoid typing ../../../ in import statements. Would be very handy if open-this supported that config and opened the files.

How this feature would work is:

1. Find webpack.config.js, if any
2. See if there are any aliases in resolve.alias
3. When open-this is executed, resolve aliases to the real path and open the right file

If you are also interested in having this feature, I'd be willing to submit a PR for it.

[t9md]

It seem to good enhancement for webpack user, I want to see PR.