Introducing zuul-discovery

zuul-discovery

• New module with a Resolver interface to decouple service discovery from Netflix's ribbon implementation. This should enable plugging in custom service discovery mechanisms.

zuul-core

• update to using Netty 4.1.63
• update to using tcnative 2.0.36
• enables optimistic caching of request bodies, regardless of SSL to origins
• refactor to extract out OriginTimeoutManager that allows for read timeout configuration.

zuul-guice

• update to Guice 5 enabling migrations beyond jdk11

Misc

• update to Gradle 6.8.2, added tests, and other minor improvements.