Use isMobileDataCapable/isVoiceCapable helpers in network/telephony settings/utils

Instead of relying exclusively on the config_show_sim_info config
option to disable telephony support, use both isMobileDataCapable()
and isVoiceCapable() helper methods to check for the telephony support
on runtime, based on the TelephonyManager capabilities.

Bug: 395714454
Test: mm && atest tests/spa_unit/src/com/android/settings/network/telephony/
Flag: EXEMPT bugfix
Change-Id: I1dc5c8fa93dea18f7f456212613200db3802253e