Add installation id for feature flags (#3052)

core/common/src/main/kotlin/mihon/core/common/FeatureFlags.kt

@@ -0,0 +1,12 @@
+package mihon.core.common
+
+import kotlin.uuid.ExperimentalUuidApi
+import kotlin.uuid.Uuid
+
+object FeatureFlags {
+
+    @OptIn(ExperimentalUuidApi::class)
+    fun newInstallationId(): String {
+        return Uuid.random().toHexDashString()
+    }
+}