Generate deprecation annotations based on OpenAPI document

[simonjbeaumont]

Motivation

The OpenAPI spec supports declaring various parts of the API as deprecated, including operations, parameters, schemas, and properties. These can be surfaced in the generated code by adding @available(*, deprecated) annotations to the functions, types, and properties.

Modifications

• Support for deprecated OpenAPI schemas.
• Support for deprecated OpenAPI properties.
• Support for deprecated OpenAPI operations.

For deprecated operations, these are annotated on the function requirements in the generated APIProtocol.

Result

Deprecated annotations are generated for the parts of the API marked as deprecated in the OpenAPI document.

Test Plan

• Added #/components/schemas/DeprecatedObject to reference test.
• Added #/components/schemas/ObjectWithDeprecatedProperty to reference test.
• Marked #/paths//probe//post operation as deprecated in reference test.
• Marked #/components/parameters/My-Request-UUID parameter as deprecated in reference test.
• Unit tests for rendering DeprecatedDescription already existed.

Resolves

Resolves #26.

[simonjbeaumont]

Heh... I hadn't considered that our CI is building with warning-as-error and that this now generates a warning because there's deprecated symbols:

/code/Tests/PetstoreConsumerTests/TestClient.swift:44:29: error: 'probe' is deprecated
        _ input: Operations.probe.Input
                            ^
/code/Tests/PetstoreConsumerTests/TestClient.swift:45:34: error: 'probe' is deprecated
    ) async throws -> Operations.probe.Output {
                                 ^
[215/342] Compiling PetstoreConsumerTests Test_Client.swift
error: fatalError
1
Build step 'Execute shell' marked build as failure

Will update the flags in the CI build.

[czechboy0]

Looks great, thanks! Just added a few nits.

[czechboy0]

Looks great!

[czechboy0]

Changing from semver/minor to semver/patch, as it only causes a build error if you explicitly opt in to warnings as errors, in which case we don't consider that a semver break.