HM-389: Add k-value validation result handling functionality in central node.

1. What this MR does / why we need it:

• This MR handles the k-value validation results received from the respected dish leaf nodes.
• Aggregates the result codes received from dish leaf nodes.
• Sets the dishVccValidationStatus attribute as per the validation.

2. Make sure that you've checked the boxes below before you submit MR:

• No conflict with master branch.
• Merge Request Title appropriate.
• Unit/Integration tests added and existing test cases are passing.
• Variable and Function names state the purpose.
• There is no commented out code, print/debug statements.
• Logs are added wherever necessary.
• Exception is handled wherever required.