Fix Voice Transfers

[murilovmachado]

Description

This is a temporary fix to the voice transfers issue we're having on SG STG.

The main thing here is:

• When transferring a call
• Right before it happens, we check if the task attributes contains conference info
• If not, we update the task attributes to include it
• And transfers will work after that

This PR also fixes:

• Mute feature: it now doesn't look at the task attributes anymore

This PR doesn't fix:

• It does not fix the root cause
  • That is: why conference is not the task attributes when the call is accepted
• Right after the transfer is succeeded, the original counselor gets a 500 on the chrome console:
  • POST https://serverless-3066-production.twil.io/conference/updateParticipant 500
  • Probably because callSid is undefined

Other Related Issues

https://tech-matters.atlassian.net/browse/CHI-2847