Generalize BlockIndexVector #283

Job	Run time
IntegrationTest (GradedArrays) / GradedArrays	10m 6s
IntegrationTest (KroneckerArrays) / KroneckerArrays	7m 55s
IntegrationTest (NamedDimsArrays) / NamedDimsArrays	4m 21s
IntegrationTest (QuantumOperatorDefinitions) / QuantumOperatorDefinitions	4m 52s
IntegrationTest (ITensorBase) / ITensorBase	2m 56s
IntegrationTest (FusionTensors) / FusionTensors	7m 0s
	37m 10s

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