[mDNS] pretty print txt values in log
Without this commit, the Thread service logs look like:
```
03-27 14:50:07.033 739 1924 I NsdPublisher: Registering service. Listener ID: 1, serviceInfo: name: Android Thread Border Router #2CF8, type: _meshcop._udp, subtypes: , hostAddresses: , hostname: null, port: 49152, network: null, expirationTime: null, txtRecord: id=֞�"ҽD���.�j���nn=OpenThreadrv=1sb=������tv=1.3.0
03-27 14:50:07.033 739 1924 I NsdPublisher: vn=Android
xa=Q�;�P,�
xp=ޭ��������
```
With this commit, the Thread service logs look like:
```
03-27 13:37:31.672 741 1925 I NsdPublisher: Registering service. Listener ID: 1, serviceInfo: name: Android Thread Border Router #7CE8, type: _meshcop._udp, subtypes: , hostAddresses: , hostname: null, port: 49152, network: null, expirationTime: null, txtRecord: {id=0x70A5AE087668D7522919F40D1684D182, mn=Thread Border Router, nn=OpenThread, rv=1, sb=0x00000021, tv=1.3.0, vn=Android, xa=0x06EC93E283A47CE8, xp=0xDEAD00BEEF00CAFE}
```
Bug: 329366417
Change-Id: I6b15e93ad117f4ebb5762df85e359a705bd65b7d
2 files changed