Split out the nsd API surface and use framework-connectivity-tiramisu

- Split out nsd APIs and hidden APIs to Connectivity module.
- Keep the all files in f/b/packages/Connectivity-T and add
  framework-connectivity-tiramisu library on p/m/Connectivity.
  Then make framework to use this module library.
- Remove NsdService from SystemServer which will register from
  ConnectivityServiceInitializer

Bug: 206893064
Test: m online-sdk-dev-docs
Test: atest FrameworksNetTests CtsNetTestCases
CTS-Coverage-Bug: 207804007
Merged-In: I72c7de124b9cc53f2263bd452ecd5f39e88e485b
Change-Id: I72c7de124b9cc53f2263bd452ecd5f39e88e485b

services/java/com/android/server/SystemServer.java

@@ -1338,7 +1338,6 @@ public final class SystemServer implements Dumpable {
         VcnManagementService vcnManagement = null;
         NetworkStatsService networkStats = null;
         NetworkPolicyManagerService networkPolicy = null;
-        NsdService serviceDiscovery = null;
         WindowManagerService wm = null;
         SerialService serial = null;
         NetworkTimeUpdateService networkTimeUpdater = null;
@@ -1941,16 +1940,6 @@ public final class SystemServer implements Dumpable {
             }
             t.traceEnd();
 
-            t.traceBegin("StartNsdService");
-            try {
-                serviceDiscovery = NsdService.create(context);
-                ServiceManager.addService(
-                        Context.NSD_SERVICE, serviceDiscovery);
-            } catch (Throwable e) {
-                reportWtf("starting Service Discovery Service", e);
-            }
-            t.traceEnd();
-
             t.traceBegin("StartSystemUpdateManagerService");
             try {
                 ServiceManager.addService(Context.SYSTEM_UPDATE_SERVICE,