feat: added xtasks fetch and code-gen to generate code

[haydenhoang]

Change Summary

cargo xtask fetch will fetch the api spec from this repository and overwrite the openapi.yml.

cargo xtask code-gen will preprocess the openapi.yml and write it to preprocessed_openapi.yml then run the codegen via Docker.

As to why we need to preprocess the open api spec file: some of the URL parameters are defined as object type (SearchParameters, MultisearchParameters,...) which are invalid. The preprocess step basically flatten the object into individual URL parameters.

Also added compose.yml to start a typesense server locally for future testing.

PR Checklist

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[haydenhoang]

Hi @morenol, for context: #47

For easier review, this is a split PR of #47, the next PR will add the multi-node client.

[morenol]

LGTM, just small nit not sure if this should be run on CI and create a PR on intervals?

[haydenhoang]

The tests should pass now.

just small nit not sure if this should be run on CI and create a PR on intervals?

Could be, but for now let's just run it manually.