tl;dr: add "internal" as a valid audience designation, with functionality set "published".
Details
- adjust [[ https://gerrit.wikimedia.org/g/mediawiki/core/+/1eeccc2d758e5c7e829fe6380954de5e9343f14f/tests/phpunit/structure/RestStructureTest.php#373 | the regexes in RestStructureTest::testModuleDefinitionFiles() ]]to allow "internal"
- remove the TODO comments about allowing other suffixes (because now the multiple-suffix pattern will be established)
- add "internal" to the mapping of audience designations to functionality sets (from T422754: REST: Audience Designations - functionality sets, following the pattern established under that task)
Note: "internal" may need careful handling as the audience designation system is introduced to avoid displaying anything in the REST Sandbox that we don't want there.