Make the runner dependencies (`web-ext`, `web-ext-run`, `@wxt-dev/runner`) peer

[aklinker1]

Feature Request

It's really annoying to manage the web-ext-run fork, leading to out-of-date error and bugs already fixed in the upstream web-ext repo.

I created the fork to reduce dependencies and WXT's install size in node_modules, but if these are peer dependencies, it solves several problems:

1. Smaller install size from WXT (technically)
2. Projects control and manage the runner version, meaning they can get updates sooner
3. WXT can look at the installed packages and easily switch between runners for each package

Is your feature request related to a bug?

Related to #1700.

What are the alternatives?

Continue shipping them as a sub-dependency.

Additional context

N/A