ref: move to Ferrum's new JavaScript API - #350

Summary

Moves Cuprite off the old evaluate_on / evaluate_async helpers to Ferrum's new JavaScript API.

• Node scripts go through node.evaluate(...) instead of evaluate_on(node:, expression:)
• Page#set passes the value as an argument to node.evaluate rather than resolving the object id by hand
• parents uses a function declaration, so it returns nodes on every Ferrum version
• trigger(:click) waits for navigation with Ferrum's wait_for_navigation!
• drag_by scrolls with Ferrum's mouse.scroll_by
• Browser#evaluate_async wraps the script in a promise built on evaluate with a timeout

Fix

Node#[] now uses the property only when it's a string, number, or boolean, and reads the attribute otherwise. Before, a property holding a node (for example input.form) came back as a node instead of the attribute value.

Tests

• Triggered click waits for the page it opens to load
• Node#[] returns the attribute for a property that holds a node