DDSXML11 — Add support for specifying the domainTag

In the DDS specification domains are identified by a integer domainId. This was expanded in the DDS-RTPS and DDS-Security specifications to also allow identification with a domainTag string. So the Domain is ultimately identified by a unique value of the tuple (domainId, domainTag).
The core DDS has not been revised in a while but there is an issue filed to add it (DDS15-258).

References:

• RTPS version 2.5, Table 8.78 says:

  domainId	DomainId_t	Identifies the DDS domainId of the associated DDS DomainParticipant.
  domainTag	string	Identifies the DDS domainTag of the associated DDS DomainParticipant.

• DDS Security 10.4.1.2.5.1
  On the "domain" element that appears in the Governance file:
  The value in this element identifies the DDS domains to which the rule applies. DDS domains are identified by their DomainId (an integer) and a DomainTag (a string). One or more DomainId values (or ranges) must always be specified. In addition, one or more DomainTag values or DomainTagExpression values may be optionally specified.
  If no DomainTag and DomainTagExpression is specified, then it shall be treated as if the empty string ("") was specified as the only DomainTag value.
  Example:

      <domains>
          <id>0</id>
          <id_range>
          <min>10</min>
          <max>20</max>
          </id_range>
          <tag>Robot15</tag>
          <tag_expression>AGVS/*</tag_expression>
      </domains>