Add MongoDB Atlas Vector Store Auto-Configuration and Boot Starter

[tzolov]

After the addition of MongoDB Atlas Store, to make most of it we need:

• Add auto-configuration under the https://github.com/spring-projects/spring-ai/tree/main/spring-ai-spring-boot-autoconfigure/src/main/java/org/springframework/ai/autoconfigure/vectorstore
  Make sure to add the auto-configuration class to the https://github.com/spring-projects/spring-ai/blob/main/spring-ai-spring-boot-autoconfigure/src/main/resources/META-INF/spring/org.springframework.boot.autoconfigure.AutoConfiguration.imports
• Add Boot starter under the https://github.com/spring-projects/spring-ai/tree/main/spring-ai-spring-boot-starters and register the boot-starter dependency to the BOM: https://github.com/spring-projects/spring-ai/blob/main/spring-ai-bom/pom.xml