Add blockfrost mode to hydra-chain-observer #5458

Job	Run time
Benchmarks (hydra-node, tx-cost, --output-directory $(pwd)/../benchmarks)	31m 29s
nix flake check	35m 21s
Benchmarks (hydra-node, micro, -o $(pwd)/../benchmarks/ledger-bench.html)	29m 42s
Build & test (plutus-cbor)	1m 10s
Benchmarks (hydra-cluster, bench-e2e, datasets datasets/1-node.json datasets/3-nodes.json --outpu...	5m 8s
Benchmarks (plutus-merkle-tree, on-chain-cost, $(pwd)/../benchmarks)	1m 16s
Build & test (plutus-merkle-tree)	1m 22s
Build specification using nix	1m 25s
Build & test (hydra-plutus)	1m 7s
Build & test (hydra-tui)	2m 53s
Build haddock using nix	1m 5s
Build & test (hydra-node)	5m 7s
Build & test (hydra-tx)	1m 50s
Build & test (hydra-cluster)	7m 59s
Publish test results	14s
Documentation	2m 47s
Publish benchmark results	5s
	2h 10m 0s

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