Feature/306 use arrow schema instead of parquet schema in gql and cli

[Wizzy-wooz]

Description

Closes: https://github.com/kamu-data/kamu-cli/issues/306

Done:

1. Updated QueryService::get_schema() to return Arrow schema sourced from SetDataSchema event.
2. Existing logic that returns schema of the last Parquet file in the dataset has been moved into get_schema_parquet() method.
3. Updated kamu inspect schema command and renamed json format to parquet-json. Introduced arrow-json output format.
4. Used serde tp convert arrow to json.
5. Updated current_schema() GraphQL API Extend DataSchemaFormat with ArrowJson.

To do after review:

1. Create a kamu-web-ui ticket to migrate schema displayed to ArrowJson.
2. Add more tests?

Checklist before requesting a review

• [ ] CHANGELOG.md updated
• [ ] API changes are backwards-compatible
• [ ] Workspace layout changes include a migration
• [ ] Documentation update PR: <link or N/A>
• [ ] Dataset pipelines update scheduled if needed
• [ ] Unit-tests added