Add Proc macro server #7404

Job	Run time
build test linux x86-64	3m 52s
check-rust	1m 45s
build test windows x86-64	12m 32s
check-website	10s
scarb-metadata compatibility check	47s
doc tests	3m 13s
test linux x86-64 1/8	1s
test linux x86-64 2/8	1s
test linux x86-64 3/8	1s
test linux x86-64 4/8	1s
test linux x86-64 5/8	1s
test linux x86-64 6/8	1s
test linux x86-64 7/8	1s
test linux x86-64 8/8	1s
test windows x86-64 1/8	13m 25s
test windows x86-64 2/8	16m 12s
test windows x86-64 3/8	13m 46s
test windows x86-64 4/8	12m 47s
test windows x86-64 5/8	11m 8s
test windows x86-64 6/8	9m 27s
test windows x86-64 7/8	8m 27s
test windows x86-64 8/8	9m 55s
	1h 57m 34s

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