improvement(options): make the options page open in a sub-window

[WofWca]

Basically revert #120 (5ff4ca80d44b6a98168e23466eb8d17d9c26a809), except maybe keep it for Edge, unless #98 can be properly fixed as well.

We already do different builds for different browsers: https://github.com/WofWca/jumpcutter/blob/5ff4ca80d44b6a98168e23466eb8d17d9c26a809/webpack.config.js#L32