Add support for WASM backend #3345

Job	Run time
nix-build	34m 18s
cabal	6h 0m 18s
runghc	16s
unit-tests	16s
plan-extra-hackages	6h 0m 17s
shellFor-hoogle	6h 0m 17s
hydra-ifdLevel-2	20m 18s
hydra-ifdLevel-0-and-1	9m 34s
closure-size	9s
shellFor-single-package	6h 0m 17s
cabal-doExactConfig	15s
build-extra-hackages	17s
multi-target	52s
tests-benchmarks	20s
hix	1h 3m 37s
shellFor-multiple-package	30s
shellFor-not-depends	33s
maintainer-scripts	13s
docs	2h 30m 21s
hydra-ifdLevel-3	30m 18s
hydra-without-remote-builders-ghc967	1m 28s
check-path-support	57s
update-docs	8s
hydra-without-remote-builders-ghc9102	1m 37s
hix-cabal	6m 33s
haskell-nix-roots-do-not-require-IFDs	25s
check-nix-tools	1m 21s
check-materialization-concurrency	25s
	1d 5h 26m 10s

Provide feedback