0x Standard Relayer API v2 Finalized

The new Standard Relayer API spec has been finalized and is ready to be implemented. The update is prompted by a corresponding update in the 0x protocol itself (see the spec here). For SRA v2, we are still working on updating some our tooling (such as sra-report, and connect) and have opted to define the REST API using the OpenAPI specification (website, repo). This will plug us into a rich ecosystem of open source software compatible with OpenAPI, and make future updates to SRA easier.