sourcegen: batch calls to same script for different cross projects (#… #1189

Job	Run time
Native image build on ubuntu-20.04	4m 53s
build	3m 13s
Native image build on macos-13	6m 36s
Native image build on macos-latest	4m 41s
Native image build on windows-latest	6m 30s
release	0s
	25m 53s

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