[WIP] Removed non-v1 (non EP) swap quote consumers

[alexkroeger]

Description

A refactor to remove asset-swapper code that's irrelevant to 0x API v1. v0 code will live on in a frozen image.

Testing instructions

Types of changes

Checklist:

• [ ] Prefix PR title with [WIP] if necessary.
• [ ] Add tests to cover changes as needed.
• [ ] Update documentation as needed.
• [ ] Add new entries to the relevant CHANGELOG.jsons.