Enhance explorer observations with chain time #2988

Job	Run time
Build haddock using nix	1m 46s
Build specification using nix	55s
Build & test (plutus-cbor)	2m 5s
Benchmarks (hydra-node, tx-cost, --output-directory $(pwd)/../benchmarks)	3m 7s
Build & test (plutus-merkle-tree)	1m 53s
Benchmarks (hydra-node, micro, -o $(pwd)/../benchmarks/ledger-bench.html)	2m 38s
Build & test (hydra-plutus)	1m 52s
Benchmarks (hydra-cluster, bench-e2e, datasets datasets/3-nodes.cbor datasets/1-node.cbor --outpu...	5m 27s
Build & test (hydra-tui)	2m 40s
Benchmarks (plutus-merkle-tree, on-chain-cost, $(pwd)/../benchmarks)	1m 57s
Build & test (hydra-node)	4m 45s
Build & test (hydra-cluster)	10m 34s
Publish benchmark results	8s
Documentation	1m 30s
Publish test results	13s
	41m 30s

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