fix(meilisearch): add Meilisearch community module

[dmi03]

Adds a community module for Meilisearch. There is no Python module yet,
although Java, Go and Rust have one.

Two things worth a look during review:

• No client library is required. Readiness is detected with
  HttpWaitStrategy against /health, so the extra is declared as
  meilisearch = []. The official meilisearch client is only added
  to the test dependency group.
• The container runs in production mode by default, which makes a
  master key mandatory. A random one is generated when none is given
  and exposed via get_master_key(). Keys shorter than 16 bytes are
  rejected in the constructor, since Meilisearch would otherwise refuse
  to boot with a confusing error.