Support passing custom annotations to generated code

With the work in PR https://github.com/mapstruct/mapstruct/pull/2792 being done for https://github.com/mapstruct/mapstruct/issues/1574 it would be good to provide some support for the new API in the IntelliJ plugin as well.

Some things that we should do:

• Auto completion support for AnnotateWith.Element#name and error when name does not exist in target enum.
• Smart auto completion for AnnotateWith.Element#classes (pick the class type based on the one in the annotation
• Auto completion for AnnotateWith.Element#enums and error when enum value does not exist
• Annotation cannot annotated the generated class / method (it doesn't have the right target element type)
• Error when more than one value type is provided, eg. shorts() and strings()
• Error when duplicated AnnotateWith.Element#name (more than one having the same name
• Error when value does not match target annotation value type
• Error when using array value, but target value is not an array

首先阅读 PR #2792 和 issue #1574，了解新的 AnnotateWith API，然后检查 IntelliJ 插件现有的生成注解支持。完成标准是实现并验证列出的补全和错误检查，包括目标兼容性、重复名称、值类型和数组。