Show VM activating in settings

When a user enters the voicemail settings page and the voicemail is still being activated, we need to show the "Activating...." string to tell the user that something is still happening. This is important since unless the activation has happened, other settings are not visible e.g transcription and donation

Bug: 76107888
Test: N/A
PiperOrigin-RevId: 189970472
Change-Id: Ib9eeee64cd67c2adc4830a743516851ffa637fbf