Introduce API versioning for ENS Referrals APIs

[lightwalker-eth]

Prerequisites

Before beginning this issue, we should first complete:

• Flip dependency relationship between the ens-referrals and ensnode-sdk packages #1519

Background info

1. We urgently need to ship some updates to the referral-related APIs that currently live in ENSApi.
2. The urgent updates we need to ship will include a bunch of breaking changes.
3. This creates a significant change management problem.
   1. We must avoid breaking or blocking the ability for Jedrzej to continue shipping updates to ENSAwards.
   2. It is operationally complex for us to deploy updates to ENSApi -- especially to coordinate these updates with concurrent updates to ENSAwards that we merge at basically the same moment that we update the production deployment of ENSApi.

Suggested strategy

1. Instead of making any changes to the existing referral-related APIs that currently live in ENSApi, we can instead create completely new referral-related APIs.
2. Assume an implicit /v0/... route prefix on all existing referral-related APIs.
3. Effectively copy-paste the existing referral-related API implementations under an explicit /v1/... route.
   1. The targeted outcome of this is that both the v0 and v1 implementations of these APIs will both exist and be exactly identical (initially!) Therefore, the PR associated with this issue has the goal of just making both of these API routes distinct but ultimately exactly identical.
   2. In future issues / PRs we will work to evolve the v1 implementation of these APIs to meet the new requirements while keeping the v0 implementation of these APIs completely unchanged.
4. We will complete the (many!) significant breaking changes to the v1 implementation of these APIs while keeping the ENSAwards site on the v0 implementation of these APIs. Many updates are needed and will be completed across multiple PRs.
5. Once the v1 implementation of these APIs is stable and deployed into production, we can create a PR for ENSAwards to transition all of its logic to the v1 implementation of these APIs.
6. Once ENSAwards completes the transition of all its logic to the v1 implementation of these APIs, we can completely delete the v0 implementation of these APIs.

Goals for the PR associated with this issue

1. Complete items 1, 2, and 3 from the "Suggested strategy" listed above. Items 4, 5, and 6 can be outside the scope of the PR associated with this issue.
2. Introduce zero changes that would break the ENSAwards site.