Add support for WASM backend #3178

Job	Run time
check-materialization-concurrency	24s
build-extra-hackages	40s
cabal-doExactConfig	56s
cabal	1m 10s
check-path-support	36s
closure-size	7s
docs	12m 3s
haskell-nix-roots-do-not-require-IFDs	48s
hix	1m 11s
hix-cabal	15s
hydra-ifdLevel-0-and-1	5m 53s
hydra-ifdLevel-2	11m 0s
hydra-ifdLevel-3	30m 14s
hydra-without-remote-builders-ghc9102	2m 41s
maintainer-scripts	8s
hydra-without-remote-builders-ghc967	5m 24s
multi-target	43s
nix-build	4m 55s
nix-tools	15s
runghc	12s
plan-extra-hackages	9s
shellFor-hoogle	18s
shellFor-multiple-package	18s
shellFor-not-depends	21s
shellFor-single-package	22s
tests-benchmarks	38s
unit-tests	9s
update-docs	9s
	1h 21m 59s

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