ghc-wasm-meta: Allow disabling head.hackage in setup.sh

CI started failing due to head.hackage merging a change that's incompatible with the GHC built by ghc-wasm-meta. Currently, I have to manually edit setup.sh to not run wasm32-wasi-cabal update and manually run rm ~/.ghc-wasm/.cabal/config to disable head.hackage.

More information at this commit: https://github.com/fourmolu/fourmolu/pull/334/commits/0a186b1c60ce6a279b62794886ab7aea11ed65ae

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information