More semantic event handling for Unarchiver / Archivers

[codedread]

Like was done for commit c3a7b35, we could remove all the Unarchive Event sub-classes in archive/events.js and replace them with @typedef data structures and attach to CustomEvents.

I want to do this for two reason:

• It provides a better DX for subscribing to events with methods like onExtract() that the IDE can give hints for. We can keep addEventListener() around for backwards-compatibility.
• It aligns the archive package with the image package.