Introducing workers.new, custom builds, and improved logging for Workers

What this post added

Introduced `workers.new` for instant JavaScript editor access to create and test Workers. Enhanced `wrangler` with custom build script support, allowing developers to use any JavaScript bundler (webpack, Rollup, Parcel, esbuild) for more complex deployments. Improved `wrangler tail` with a new 'pretty' output format for easier log and exception readability.