Bug 1932219 - Add focus to performance-artifact.json (#8305)

Add focus to the performance-artifact-schema so focus results can be ingested

schemas/performance-artifact.json

@@ -13,6 +13,7 @@
             "geckoview",
             "refbrow",
             "fenix",
+            "focus",
             "safari",
             "safari-tp",
             "custom-car",