Moving all Telephony overlays to CarrierConfigManager.

This adds every variable and its default value from
packages/services/Telephony/res/values/config.xml to the new
CarrierConfigManager API. Variable docstrings are also taken from
config.xml, with minimal edits.

These variables were not included because either they are not carrier
specific, or they are device specific:

OtaPlaySuccessFailureTone
OtaShowActivateFailTimes
OtaShowActivationScreen
OtaShowListeningScreen
carrier_settings
carrier_settings_menu
config_allow_hfa_outside_of_setup_wizard
config_enabled_lte
csp_enabled
dialer_default_class
dtmf_type_enabled
hac_enabled
send_mic_mute_to_AudioManager
ui_default_package

This also adds BOOL_HIDE_CARRIER_NETWORK_SETTINGS which is a replacement
for android.provider.Settings.Global.HIDE_CARRIER_NETWORK_SETTINGS.

Bug: 20270007
Change-Id: I985a55cf88d3bd1863e28af7790b59eef01d6504