this commit is mostly to figure out hwo to build a yew application in
depot using the wasm toolchain. it's a bit finnicky, but could be a
lot worse.
Change-Id: I7804a774f1686a1f308ae1a3f549cd0ae7b5dbeb
Reviewed-on: https://cl.tvl.fyi/c/depot/+/5980
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>