test: move domain tests to tests/

Self dev-dep w/ test-helpers for domain::testing. Also moved social blanket-impl + InMemoryStore tests (public API only). No private-item exceptions.

crates/domain/tests/services.rs

@@ -0,0 +1,6 @@
+#[path = "services/insights_analyzer_test.rs"]
+mod insights_analyzer_test;
+#[path = "services/review_history_test.rs"]
+mod review_history_test;
+#[path = "services/wrapup_analyzer_test.rs"]
+mod wrapup_analyzer_test;