Fix Elytron Enabled attributes at ResourceAdapters subsystem

This Jira is for all ELYTRON_ENABLED attributes defined in resource adapters subsystem.
The attribute definition has two bugs:

• alternatives defined:
  The alternative prevents the user from setting an ELYTRON_ENABLED attribute to false and using one of the alternative attributes, such as SECURITY_DOMAIN because the model will be considered invalid.

The correct is using alternatives at the AUTHENTICATION_CONTEXT attributes instead and doing an extra validation at RaAdd.

• marshalling of the attribute, we need to follow the same standard as other boolean attributes in the module, the attribute must be marshalled as a <elytron-enabled>true</elytron-enabled> instead of <elytron-enabled/>, which is the current form being used now