feat: support JSON schemas in the FillEntityDefaults function

FillEntityDefaults can be used to inject Kong entity defaults
into a Kong entity struct. This function achieves this by getting
entity schemas from the Admin API, flattening the returned schemas
and merging these with the input schemas.

Kong CP only works with Lua schemas, while Konnect also supports
JSON schemas.

This commit adds support to filling entity defaults from JSON schemas.

CHANGELOG.md

@@ -1,5 +1,6 @@
 # Table of Contents
 
+- [Unreleased](#Unreleased)
 - [v0.33.0](#v0330)
 - [v0.32.0](#v0320)
 - [v0.31.1](#v0311)
@@ -41,6 +42,13 @@
 - [0.2.0](#020)
 - [0.1.0](#010)
 
+## [Unreleased]
+
+> Release date: TBD
+
+- Add support to Kong Vaults
+  [#224](https://github.com/Kong/go-kong/pull/224)
+
 ## [v0.33.0]
 
 > Release date: 2022/10/05
@@ -619,6 +627,7 @@ authentication credentials in Kong.
   releases of Kong since every release of Kong is introducing breaking changes
   to the Admin API.
 
+[Unreleased]: https://github.com/Kong/go-kong/compare/v0.33.0...Unreleased
 [v0.33.0]: https://github.com/Kong/go-kong/compare/v0.32.0...v0.33.0
 [v0.32.0]: https://github.com/Kong/go-kong/compare/v0.31.1...v0.32.0
 [v0.31.1]: https://github.com/Kong/go-kong/compare/v0.31.0...v0.31.1