Use Serde for aws-alexa-httpserver

[sdelamo]

Try to use serde for aws-alexa-httpserver.

see: https://github.com/micronaut-projects/micronaut-aws/blob/master/aws-alexa-httpserver/src/main/java/io/micronaut/aws/alexa/httpserver/controllers/SkillController.java#L20

We will need to use @SerdeImport

https://micronaut-projects.github.io/micronaut-serialization/latest/guide/#serdeImport

[timyates]

We've tried this before, and until Serde allows Builders, I don't think it's possible #1323 (comment)