Deduplicate external contracts by full path #9113

Job	Run time
check-rust (nightly)	43s
build test linux x86-64	5m 25s
check-rust	1m 6s
build test windows x86-64	14m 12s
check-website	9s
scarb-metadata compatibility check	22s
doc tests	1m 1s
test nightly crates linux x86-64	6m 58s
snforge-init	1m 37s
test linux x86-64 1/4	4m 11s
test linux x86-64 2/4	4m 25s
test linux x86-64 3/4	4m 8s
test linux x86-64 4/4	3m 21s
test windows x86-64 1/4	6m 19s
test windows x86-64 2/4	6m 47s
test windows x86-64 3/4	6m 0s
test windows x86-64 4/4	4m 53s
	1h 11m 37s

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