Use a builder format for the allpages generator

Add more filtering options in an optional manner. I'm not super satisfied with the typed-builder generator, but it seems like the closest off-the-shelf macro I can find for now. Presumably we need or want something to generate the rest of the generate() function parameter mapping.

Since we're adding extra dependencies and likely to write our own macro, I moved the generator system under a default feature. This is partly because wasm32 support doesn't work with our use of tokio::spawn() and this gives us an out.

Bug: T319113 Bug: T322502