[Fix #1356] Enhance `Rails/DuplicateAssociation` to handle alias #528

Job	Run time
Check the oldest supported RuboCop version	27s
Spec - JRuby	1m 36s
Spec - 2.7	26s
Check documentation syntax	14s
Spec - 3.0	22s
Prism	28s
Spec - 3.1	22s
Spec - 3.2	15s
Spec - 3.3	14s
Spec - 3.4	17s
Spec - head	15s
	4m 56s

Provide feedback