Option to set Agent NodeName via API

Please search the existing issues for relevant feature requests, and use the reaction feature (https://blog.github.com/2016-03-10-add-reactions-to-pull-requests-issues-and-comments/) to add upvotes to pre-existing requests.

#### Feature Description

We have an option to get the nodeName of agenthttps://godoc.org/github.com/hashicorp/consul/api#Agent.NodeName
Need to expose an option to set Agent Node Name

#### Use Case(s)

While using consul api , the agent node Name is dynamically determined at runtime. This hinders to set NodeName while doing proxy consul registration

Start by reviewing the Consul API entry point for Agent.NodeName and search existing issues for related feature requests. Determine how an API-set node name should support proxy Consul registration, then verify that the behavior is covered by the relevant API tests.

Written by the indexing model from the issue text.