Add an option that dumps package details to JSON (#3293) #709

Job	Run time
initialise	5s
quick-check	5m 32s
ubuntu-bootstrap-chez	7m 18s
nix-bootstrap-chez	19m 51s
macos-bootstrap-chez	12m 30s
ubuntu-bootstrap-racket	12m 0s
ubuntu-self-host-previous-version	10m 52s
windows-bootstrap-chez	22m 54s
ubuntu-build-api	3m 58s
ubuntu-self-host-chez	10m 53s
ub-test-collie	21s
ub-test-frex	1m 30s
ub-test-elab-util	40s
ub-pack-test-lsp	14m 15s
ub-pack-test-pack	11m 30s
ub-test-katla-and-html	6m 19s
ubuntu-self-host-racket	0s
macos-self-host-chez	14m 7s
windows-self-host-racket	11m 38s
	2h 46m 13s

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