Use srsly for JSON serialization

[prrao87]

Updates

• srsly is a fast and lightweight JSON serialization library from Explosion.

  • It eliminates a lot of boilerplate for util functions that read/write compressed JSONL files (in gzip format)
  • Using this library each bulk indexing script is very simple, doesn't add much overhead to the pip install time, and reduces the number of lines of code quite significantly
  • The code base for Elasticsearch, Meilisearch and Neo4j have all been updated to use srsly to read gzipped JSONL
  • For future DBs, the same approach will be used to also keep things clean and readable

• For Meilisearch, the settings specification is moved over to a settings.json to keep things clean and easy to find all in one place