POC of Default inline resolver with showcase

[Simply007]

Motivation

Allow defining a default inline rich text resolver as a fallback when no other resolver is used.

Checklist

• [ ] Code follows coding conventions held in this repo
• [ ] Automated tests have been added
• [ ] Tests are passing
• [ ] Docs have been updated (if applicable)
• [ ] Temporary settings (e.g. variables used during development and testing) have been reverted to defaults

How to test

If manual testing is required, what are the steps?

[Simply007]

Described on: https://github.com/Kentico/kontent-java-packages/wiki/Rich-text-resolution#completely-custom-template-configuration-ie-default-fallback-rich-text-element-resolver