Updates to validate support for RFC 9154

[gbicann]

Note

This change will only be implemented if the support for RFC 9154 becomes mandatory as a result of a change to the Transfer Policy.

Update the EPP and SRS Gateway test suites to check support for RFC 9154.

Since epp-19 already supports it, all that's needed is to ensure that epp-02 checks for the namespace URI in the server <greeting>.

Internal ref: NRRST-1267 & NRRST-1268