chore: Use utoipa to generate open-api schemas from the code

[squadgazzz]

Background

Currently, the OpenAPI documentation is maintained manually with openapi.yml. This approach requires regular manual updates to ensure the API documentation stays in sync with the codebase, which is time-consuming and prone to human error.

Proposal

Migrating to utoipa for automatic generation of OpenAPI documentation directly from our code.

Acceptance criteria

• OpenAPI files are generated automatically and e2e tests pass

[squadgazzz]

Discussion: cowprotocol/pm#23

[fleupold]

Contributions to automatically deriving any of these API definitions would be very welcome:

1. https://github.com/cowprotocol/services/blob/main/crates/solvers/openapi.yml
2. https://github.com/cowprotocol/services/blob/main/crates/driver/openapi.yml
3. https://github.com/cowprotocol/services/blob/main/crates/orderbook/openapi.yml

Exploring libraries other than utoipa is also possible.

[Flugplatz]

@fleupold I've raised an inital PR here for discussion: #2338