Add type class roots to weeder and remove unused type classes. #6668

Job	Run time
Build & test (hydra-plutus)	1m 19s
Build & test (hydra-tui)	3m 7s
Build & test (hydra-node)	7m 19s
Build & test (hydra-tx)	1m 54s
Build specification using nix	1m 25s
Benchmarks (hydra-node, tx-cost, --output-directory $(pwd)/../benchmarks)	2m 3s
Build & test (hydra-cluster)	11m 24s
Benchmarks (hydra-node, micro, -o $(pwd)/../benchmarks/ledger-bench.html)	1m 34s
Build haddock using nix	1m 0s
nix flake check	4m 57s
Benchmarks (hydra-cluster, bench-e2e, datasets datasets/1-node.json datasets/3-nodes.json --outpu...	3m 56s
Compute cost differences	3m 29s
Publish benchmark results	3s
Publish test results	14s
Documentation	3m 0s
	46m 44s

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