Add plugin discovery utilities to scarb-metadata #8509

Job	Run time
build test linux x86-64	3m 15s
build test windows x86-64	10m 36s
scarb-metadata compatibility check	49s
doc tests	3m 45s
test prebuilt plugins linux x86-64	1m 22s
check-rust	4m 39s
test prebuilt plugins windows x86-64	4m 17s
check-website	9s
test prebuilt plugins macos arm64	1m 37s
snforge-init	4m 45s
test prebuilt plugins macos x86-64	2m 20s
test linux x86-64 1/4	18s
test linux x86-64 2/4	29s
test linux x86-64 3/4	2m 10s
test linux x86-64 4/4	20s
test windows x86-64 1/4	1m 28s
test windows x86-64 2/4	40s
test windows x86-64 3/4	2m 54s
test windows x86-64 4/4	48s
	46m 41s

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