feat(settings): Add sortFacetValuesBy

[ahmednfwela]

Pull Request

Related issue

Fixes #339

What does this PR do?

• Add enum FacetingSortTypes
• Add Map<String, FacetingSortTypes>? sortFacetValuesBy to Faceting
• Updated .code-samples.meilisearch.yaml
• [BREAKING] change members of Faceting to be final, and remove the default values set there.

  PR checklist

  Please check if your PR fulfills the following requirements:

• [x] Does this PR fix an existing issue, or have you listed the changes applied in the PR description (and why they are needed)?
• [x] Have you read the contributing guidelines?
• [x] Have you made sure that the title is accurate and descriptive of the changes?

Thank you so much for contributing to Meilisearch!

[ahmednfwela]

@brunoocasali looks like uploading to codecov failed for some reason, can you look into it ?

Update: looks like it's flakey, maybe due to rate limiting for not providing API key ?

[meili-bors[bot]]

Build succeeded:

• integration-tests (dart 3.0.0)
• linter-check
• pana