Switch cloudflare_worker/wrangler.toml from type = "rust" to type = "javascript"

[twifkak]

Introducing a dependency on some of the functions in encoding_rs causes a segfault in wasm-opt before version 102. However, wrangler projects with type = "rust" depend on wasm-pack 0.10.0 and wasm-pack 0.10.0 depends on wasm-opt 78.

Rather than waiting for both of these dependencies to update in sequence, we should consider switching to type = "javascript". Either:

• Grep the wrangler source code for uses of TargetType::Rust and reproduce those in toml, or
• Switch to this template, which is the new template generated by wrangler for --type rust. This would require eliminating the TypeScript and using workers-rs instead, which might have downsides -- e.g. performance loss from DOM<->Rust bridge? Or no async_std/tokio.

I learn towards the first. It seems easier and less risk, and doesn't preclude the doing second one later.