Karist should use funcml instead of re-implementing it

[mimopotato]

We should separate the Karist CLI and its mutative engine to let it be useful in other contexts than Kubernetes. Separating this project in two parts:

• the mutative language part, called "funcml-lang"
• the Karist CLI that can generate examples and apply changes to Kubernetes specifically

Karist would have a new Rubygems.org dependency: "funcml". Unit tests would not perform any test on funcml mutations but should be focus on CLI tasks, such as files generation and exception management.

[mimopotato]

funcml-lang repository: https://github.com/mimopotato/funcml-lang