Epic: NSwag v13 - Githubissues

Topic: Remove deprecated apis

Next: v14 https://github.com/RicoSuter/NSwag/issues/2181

Tasks/epics:

[x] Rename everything from Swagger to OpenApi?
- [x] Also rename JsonSchema4 to JsonSchema?
[x] Upgrade to NJsonSchema v10
- Move NSwag default settings to NJS (see SwaggerToCSharpGeneratorSettings.cs)
- https://github.com/RicoSuter/NJsonSchema/pull/806
[x] Change default setting of DefaultResponseReferenceTypeNullHandling to NotNull?
- https://github.com/RicoSuter/NSwag/pull/2215
[x] Remove document.ToJson(JsonSchemaType.OpenApi3) => now obsolete

NSwag.AspNetCore

[x] Remove GeneratorSettings from SwaggerSettings (also T)
[x] Enable IOptions support (see TODOs)
[x] Remove NSwag.SwaggerGeneration.WebApi dependency
[x] Rename property SwaggerRoute / SwaggerUiRoute to DocumentPath and UiPath? (already in v12)
[ ] ~~Use* use settings directly instead of Action => discuss this?~~

TypeScript/CSharp:

[x] Changed default exception name to ApiException (added TypeScript option, changed for CSharp)

RicoSuter / NSwag