Require the two default thread-pool and job repository attributes for the batch subsystem

Resources, such as the batch subsystem, that provide capabilities must provide ensure their capabilities are provided. Currently the default-thread-pool and default-job-repository are not required attributes. If the attributes are not defined then the org.wildfly.batch.default.thread.pool and org.wildfy.batch.default.job.repository capabilities are not fulfilled. Making the two attributes required will solve this.

One thing to consider is making the two attributes required does require that both a thread-pool and either a in-memory-job-repository or jdbc-job-repository is defined. It's possible to keep the default-job-repository optional and just use a default InMemoryJobRepository if it is undefined. A thread-pool must be defined though.