editoast: better way to infer/compute error context type

[sim51]

Description and goal

In the error derive, we compute the type of error's context ( ie list its properties and their type).

For now the code is pretty simple and do manually the cast between simple rust type and openapi.
You can check the function fn error_context_to_openapi_object in src/view/mod.rs for example.

A better way can be found to do it, specially if the error derive if we can save in inventory something that be directly given to utoapi.

Acceptance criteria

A better way to compute context type which support more types with less code

[sim51]

Some hints :

• https://github.com/rust-lang-nursery/lazy-static.rs
• https://docs.rs/utoipa/latest/utoipa/macro.schema.html