Use isMobileDataCapable helper in wifi/ components

Disabling telephony support may be done either with the
config_show_sim_info config option, or based on whether
TelephonyManager reports data capabilities. The isMobileDataCapable()
helper method ensures both ways are supported.

Bug: 395714454
Test: mm && atest tests/robotests/src/com/android/settings/wifi
Flag: EXEMPT bugfix
Change-Id: Ibc32e7a5586a26f450b6adb13ce7e435243f0eef