Add minimal Private DNS configuration info in dumpsys

Test: as follows
    - built
    - flashed
    - booted
    - adb shell dumpsys netd
Bug: 34953048
Bug: 64133961
Change-Id: Ib09353f7b681a58524f9dbe6dd79fd3dafa4ca24
diff --git a/server/ResolverController.cpp b/server/ResolverController.cpp
index e0dc9f1..1b55f29 100644
--- a/server/ResolverController.cpp
+++ b/server/ResolverController.cpp
@@ -206,6 +206,17 @@
     privateDnsTransports.erase(netId);
 }
 
+constexpr const char* validationStatusToString(ResolverController::Validation value) {
+    switch (value) {
+        case ResolverController::Validation::in_process:     return "in_process";
+        case ResolverController::Validation::success:        return "success";
+        case ResolverController::Validation::fail:           return "fail";
+        case ResolverController::Validation::unknown_server: return "unknown_server";
+        case ResolverController::Validation::unknown_netid:  return "unknown_netid";
+        default: return "unknown_status";
+    }
+}
+
 }  // namespace
 
 int ResolverController::setDnsServers(unsigned netId, const char* searchDomains,
@@ -457,6 +468,26 @@
                     static_cast<unsigned>(params.min_samples),
                     static_cast<unsigned>(params.max_samples));
         }
+        {
+            std::lock_guard<std::mutex> guard(privateDnsLock);
+            const auto& netPair = privateDnsTransports.find(netId);
+            if (netPair == privateDnsTransports.end()) {
+                dw.println("No Private DNS configured");
+            } else {
+                const auto& tracker = netPair->second;
+                dw.println("Private DNS configuration (%zu entries)", tracker.size());
+                dw.incIndent();
+                for (const auto& kv : tracker) {
+                    const auto& server = kv.first;
+                    const auto status = kv.second;
+                    dw.println("%s name{%s} status{%s}",
+                            addrToString(&(server.ss)).c_str(),
+                            server.name.c_str(),
+                            validationStatusToString(status));
+                }
+                dw.decIndent();
+            }
+        }
     }
     dw.decIndent();
 }