Implement RFC 66: Simulation time. #3542

Job	Run time
document	55s
check-links	45s
smoke (amaranth-lang/amaranth-boards)	31s
smoke (amaranth-lang/amaranth-stdio)	36s
test (3.8)	2m 15s
smoke (amaranth-lang/amaranth-soc)	36s
test (3.9)	2m 9s
test (3.10)	2m 0s
test (3.11)	2m 15s
test (3.12)	2m 15s
test (pypy-3.8)	2m 14s
test (pypy-3.9)	2m 17s
test (pypy-3.10)	2m 14s
test (3.13-dev)	2m 15s
publish-docs	9s
publish-docs-dev	0s
required	1s
publish-package	0s
publish-schemas	0s
publish-release	0s
	23m 27s

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