Change picocli-spring-boot-starter JPMS module name to info.picocli.spring.boot from info.picocli.spring

[remkop]

Related to #1608:

Change picocli-spring-boot-starter JPMS module name to info.picocli.spring.boot from info.picocli.spring.

Now that picocli-spring-boot-starter is an explicitly declared JPMS module, I noticed the inconsistent naming compared to the names of the Spring Boot dependencies themselves.

I believe info.picocli.spring.boot is a better name, and timing-wise, making this change while converting from Automatic modules to explicitly declared modules seems like a good time to make this change.