Allow easy use of a Jakarta EE 9 variant of org.glassfish:jakarta-json

Add an element equivalent to what we do for javax.* in https://github.com/wildfly/wildfly-core/blob/master/core-feature-pack/common/src/main/resources/modules/system/layers/base/org/glassfish/jakarta/json/main/module.xml#L33 for the jakarta.* package namespace.

This has no effect when an EE 8 variant of the jar is used as the jakarta package does not exist. But having it in the module.xml makes it easy to swap in an EE9 variant of the jar.