ENGCOM-5174: issue fixed #8258 - assign indices for all array inputs so that validation works properly #15383

 - Merge Pull Request #15383 from jayankaghosh/magento2:issue-8258
 - Merged commits:
   1. 113440f
   2. 874d770
   3. 84355a3
   4. d5c41b6
   5. 156ac16
   6. 65a2c17
   7. 97c03f5
   8. 224f737
   9. 908100b
   10. 38b9709
   11. 388d31d
   12. ee288c1
   13. eadcff2

Author: magento-engcom-team