SpringBoot Add support for CNB platform API 0.4

Currently CNB platform API 0.3 is supported for interaction between the Spring Boot build plugin image-building goals/tasks. We can add support for platform API 0.4 while retaining support for 0.3.

If a builder supports platform API 0.4, we can pass the env var CNB_PLATFORM_API=0.4 and command argument -process-type=web to each lifecycle phase. This will allow users more control over process types and custom commands in the generated image.