Move struct CookieTagMap{Key, Value} to Connectivity/common

Need to share struct CookieTagMap{Key, Value} with:
service/src/com/android/server/connectivity/ClatCoordinator.java
service-t/src/com/android/server/net/NetworkStatsService.java
tests/unit/java/com/android/server/connectivity/ClatCoordinatorTest.java
tests/unit/java/com/android/server/net/NetworkStatsServiceTest.java

These files only have different package name as expected.

$ diff common/src/com/android/net/module/util/bpf/CookieTagMapKey.java service-t/src/com/android/server/net/CookieTagMapKey.java
  17c17
  <- package com.android.net.module.util.bpf;
  ---
  -> package com.android.server.net;

$ diff common/src/com/android/net/module/util/bpf/CookieTagMapValue.java service-t/src/com/android/server/net/CookieTagMapValue.java
  17c17
  <- package com.android.net.module.util.bpf;
  ---
  -> package com.android.server.net;

Bug: 237369591
Test: atest ConnectivityCoverageTests
Change-Id: Ibede81376382f0dd7a032c8c988dd84c7422eece