CtsVerifier: Fail Camera ITS in case of unsupported locale

Per CTS specification Camera ITS must only be run with default
language set to English (United States). Check this and directly
fail during ITS activity initialization and when processing ITS
commands.
The python script handling of socket errors must also be modified
to appropriately notify users about this error condition.

Bug: 149922652
Test: Manual using CtsVerifier app,
python tests/scene0/test_metadata.py

Change-Id: I3a2833e2fbc8e8863f5dd13600d39e7d77cea438