`ErrorConfiguration` is already found during component-scanning of `com.netflix.spinnaker.config`.

- Use parameter injection for config properties that are still used
- Delete the unused properties that were injected
- Use a `Jackson2ObjectMapperBuilder` bean to simplify setup of the default `ObjectMapper`

- Implement `WebMvcConfigurer` instead of extending the now deprecated `WebMvcConfigurerAdapter` class
- Use `List::of` instead of `ImmutableList::of`
- Remove call to `ContentNegotiationConfigurer::favorPathExtension` as this value has been the default in Spring for a while now
- Replace `val` with `var` keyword
- Fix some grammar in docs

Use `ServiceClientProvider` from `kork-web` to create Retrofit proxy beans for `Front50Api`, `ClouddriverApi`, and `IgorApi`. Other Retrofit settings repeatedly configured here are already configured in the relevant `ServiceClientFactory` ultimately used by `ServiceClientProvider`.

- Use `ServiceClientProvider` from `kork-web` to create a Retrofit proxy bean for `FiatService`
- Use `Jackson2ObjectMapperBuilder` to create the `ObjectMapper` used for `FiatService`
- Use `withDefaults()` customizer to simplify security configuration chains