Add support for WASM

[levkk]

Feature

Add support for running Rwf applications in WASM runtimes, e.g. Coudflare workers.

TODOs

1. Remap ORM queries to PostgREST requests (avoids using a Postgres driver directly)
2. Feature-flag usage of Tokio, use wasm-bindgen where possible; disable features where it's not.