https://issues.rudder.io/issues/28055

This PR removes the lift-json import from SettingsApi.scala.
It :

• adds API tests to endpoints that were missing one
• replaces the toJson and parseJson method of each setting by an idiomatic "JsonCodec instance" in zio-json
  ➡️ the main change is about adding given JsonCodec[...] in place of lift-json. In some places, we need to use the JSON AST types since the settings are implemented in a generic way

Along the way :

• added tests for enumeratum enums (the way it was done in Fixes #24554: Use enumeratum in place of sealarate for scala3 migration #5499)
• replacing Box with Either
• replacing implicit with given