Extract MSC-related classes within wildfly-clustering-infinispan-spi into separate module

We should split the existing wildfly-clustering-infinispan-spi module into 3 modules:

• org.wildfly.clustering.infinispan.embedded.api
  + Depends only on Infinispan
• org.wildfly.clustering.infinispan.embedded.module
  + Contains custom WildFly Infinispan module code
  + Depends on org.wildfly.clustering.infinispan.embedded.api
• org.wildfly.clustering.infinispan.embedded.spi
  + Contains subsystem integration code, e.g. capability requirements, MSC services
  + Depends on org.wildfly.clustering.infinispan.embedded.api