Switch to GHC with JS backend

[deemp]

We currently use GHCJS 8.6.0.1 from the miso repo (link).

It seems to be possible to use GHCJS 8.10 (link).

However, there may be issues with build time and bundle size (ghcjs/ghcjs#821) that can be fixed (ghcjs/ghcjs#821 (comment)).

There's JavaScript FFI backend documented for GHC 9.8.1 (link).

Additionally, there are docs on JS for GHC 9.9 (link).

• Try to build the app using GHC JS backend.

[fizruk]

But why switch to an older GHC?

[deemp]

I agree, we can try to switch to something newer. Updated the issue description.