Set the name for resolver threads

The threads in the resolver are renamed, including:
  - Threads for lookup (name: Dns_<netId>_<appId>)
  - Threads for private dns validation (name: TlsVerify_<netId>)
  - Threads for NAT64 prefix discovery (name: Nat64Pfx_<netId>)
  - Threads for communicating with private dns (name: TlsListen_<netId>)
  - Threads for reconnecting private dns (name: TlsReconn_<netId>)

Example from ps -AT:
root           756  3418     1 2501400   7352 futex_wait_queue_me 0 S Dns_105_1073
root           756  3419     1 2501400   7352 do_sys_poll         0 S TlsVerify_105
root           756  3420     1 2501400   7352 do_sys_poll         0 S TlsVerify_105
root           756  3422     1 2501400   7352 do_sys_poll         0 S TlsVerify_105
root           756  3428     1 2501400   7352 do_sys_poll         0 S TlsListen_105

Also, reveal some logs for private dns validation status to facilitate
debugging analysis.

Example:
  790  4364 W resolv  : Validating DnsTlsServer on netId 100
  790  4364 W resolv  : Validation failed
  790  4366 W resolv  : Validating DnsTlsServer on netId 100
  790  4366 W resolv  : Validation success

Bug: 128404051
Test: atest --include-subdirs packages/modules/DnsResolver
Change-Id: Ide93b1099535552a8615c71353226c1aa70462e3