Added SAML identity list from !38499 to 12.7 release post

Why is this change being made?

Catching up on stale release post feature block additions, this adds !38499 (closed) to the 12.7 release post. Since this was reviewed by PMM and was available in 12.7, setting to MWPS.

Does this MR meet the acceptance criteria?

Conformity

• Added description to this MR explaining the reasons for the proposed change, per say-why-not-just-what