Add support for WASM backend #3338

Job	Run time
nix-build	10m 35s
shellFor-not-depends	51s
shellFor-single-package	2m 37s
runghc	36s
maintainer-scripts	13s
multi-target	1m 15s
cabal	33s
shellFor-hoogle	1m 47s
cabal-doExactConfig	26s
unit-tests	12s
shellFor-multiple-package	28s
plan-extra-hackages	14s
tests-benchmarks	23s
hydra-ifdLevel-2	20m 18s
hydra-ifdLevel-3	30m 19s
closure-size	9s
hix-cabal	14s
haskell-nix-roots-do-not-require-IFDs	30s
update-docs	12s
check-path-support	12s
docs	59s
build-extra-hackages	13s
hydra-ifdLevel-0-and-1	3m 54s
hydra-without-remote-builders-ghc9102	48s
hydra-without-remote-builders-ghc967	49m 18s
check-nix-tools	21s
hix	56s
check-materialization-concurrency	24s
	2h 8m 57s

Provide feedback