Modify MustUse to iterate the stack frame and collate options from all frames. #3773

Job	Run time
smoke (amaranth-lang/amaranth-stdio)	52s
smoke (amaranth-lang/amaranth-soc)	57s
document	57s
test (3.11)	2m 25s
test (3.13)	3m 49s
test (pypy-3.10)	4m 57s
check-links	56s
smoke (amaranth-lang/amaranth-boards)	37s
test (pypy-3.9)	5m 7s
test (3.14-dev)	2m 15s
test (3.12)	3m 53s
test (3.10)	2m 11s
test (pypy-3.11)	4m 50s
test (3.9)	2m 51s
publish-docs	9s
publish-docs-dev	0s
required	2s
publish-schemas	5s
publish-package	12s
publish-release	-1s
	37m 4s

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