test(ha-config-bootstrap): RED phase tests for config bootstrap (task 5.1)

- 9 Unity tests covering Req 3.1-3.5: immediate return on nonzero tag,
  all-zero peers no defer, peer tag>0 sets defer_config_fetch, probe
  error codes, deferred fetch preconditions, ha_init zero invariant
- Linker fails with undefined refs to bootstrap_config_if_needed
  and xce_probe_config_tag (expected RED proof)

src/controller/testsuite/controller_test.c

@@ -36,6 +36,7 @@ extern void test_config_repl(void);
 extern void test_worker_join(void);
 extern void test_ha_startup(void);
 extern void test_ha_election(void);
+extern void test_ha_bootstrap(void);
 
 void setUp(void) { return; }
 
@@ -141,6 +142,7 @@ int main(int argc, char* argv[])
     TEST(test_worker_join);
     TEST(test_ha_startup);
     TEST(test_ha_election);
+    TEST(test_ha_bootstrap);
 
     return UNITY_END();
 }