(feat): Add Positional Trait in Go codegen #4

Job	Run time
test_go (TestModels/Aggregate)	3m 40s
test_go (TestModels/CodegenPatches)	4m 11s
test_go (TestModels/Constraints)	4m 14s
test_go (TestModels/Constructor)	4m 10s
test_go (TestModels/Dependencies)	4m 29s
test_go (TestModels/Errors)	4m 2s
test_go (TestModels/Extendable)	4m 53s
test_go (TestModels/Extern)	4m 23s
test_go (TestModels/Positional)	4m 45s
test_go (TestModels/Refinement)	4m 32s
test_go (TestModels/Resource)	4m 46s
test_go (TestModels/SimpleTypes/SimpleBlob)	7m 9s
test_go (TestModels/SimpleTypes/SimpleBoolean)	6m 13s
test_go (TestModels/SimpleTypes/SimpleDouble)	4m 38s
test_go (TestModels/SimpleTypes/SimpleEnum)	5m 11s
test_go (TestModels/SimpleTypes/SimpleInteger)	4m 5s
test_go (TestModels/SimpleTypes/SimpleLong)	4m 38s
test_go (TestModels/SimpleTypes/SimpleString)	5m 4s
test_go (TestModels/Union)	5m 34s
test_go (TestModels/aws-sdks/kms)	4m 8s
	1h 34m 45s

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