add snake case param name

[sarron93]

Description (*)

If we created service interface when have method public function importQty(object $productQty)
after send bulk request via url rest/async/bulk/V1/my_module/qtyUpdate include body
[ { "product_qty": { "template_id": 11831, "sku": "SKU0000100863", "qty": 13.0 } }, { "product_qty": { "template_id": 11821, "sku": "SKU0000138399", "qty": 13.0 } } ] then we get 202 status code and response text
{ "bulk_uuid": "942a14e7-431f-4a68-8009-2d1671b90eed", "request_items": [ { "id": 0, "data_hash": "64172f83f6b3955c91b4ed80117d6d26b4b3f81be61371b2e4c1769c6c93cf1f", "status": "accepted" }, { "id": 1, "data_hash": "132179362258e95fad607d91cbb96c7300c7620c3665fcff3476146625189557", "status": "accepted" } ], "errors": false }
after we send get request on url rest/V1/bulk/7e989285-c171-4c7b-b9c1-f3d77a7459cc/status and see this error
{ "operations_list": [ { "id": 0, "status": 3, "result_message": "Data item corresponding to \"productQty\" must be specified in the message with topic \"async.utires.odoointegration.api.productimportmanagementinterface.importqty.post\".", "error_code": 0 }, { "id": 1, "status": 3, "result_message": "Data item corresponding to \"productQty\" must be specified in the message with topic", "error_code": 0 } ], "user_type": 1, "bulk_id": "7e989285-c171-4c7b-b9c1-f3d77a7459cc", "start_time": "2021-01-15 14:48:01", "user_id": 96, "operation_count": 2 }
because vendor/magento/framework-message-queue/MessageEncoder.php class doesn't use $snakeCaseParamName variable how vendor/magento/framework/Webapi/ServiceInputProcessor.php

Manual testing scenarios (*)

1. we sent [ { "product_qty": { "template_id": 11831, "sku": "SKU0000100863", "qty": 13.0 } }, { "product_qty": { "template_id": 11821, "sku": "SKU0000138399", "qty": 13.0 } } ] we get Service execution success

Contribution checklist (*)

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds are green)

Resolved issues:

1. resolves [Issue] add snake case param name magento/magento2#31882: add snake case param name