Follows from #2528, and should complement #2411 to implement the module import hooks.
~~Similarly to the Intl/ICU4X PR (#2478), this has a lot of trivial changes caused by the new lifetimes. I thought about passing the queue and the hooks by value, but it was very painful having to wrap everything with `Rc` in order to be accessible by the host.
In contrast, `&dyn` can be easily provided by the host and has the advantage of not requiring additional allocations, with the downside of adding two more lifetimes to our `Context`, but I think it's worth.~~ I was able to unify all lifetimes into the shortest one of the three, making our API just like before!
Changes:
- Added a new `HostHooks` trait and a `&dyn HostHooks` field to `Context`. This allows hosts to implement the trait for their custom type, then pass it to the context.
- Added a new `JobQueue` trait and a `&dyn JobQueue` field to our `Context`, allowing custom event loops and other fun things.
- Added two simple implementations of `JobQueue`: `IdleJobQueue` which does nothing and `SimpleJobQueue` which runs all jobs until all successfully complete or until any of them throws an error.
- Modified `boa_cli` to run all jobs until the queue is empty, even if a job returns `Err`. This also prints all errors to the user.
José Julián Espina
5ab0aa21cc