Adding voicemail donation promo

This cl shows a voicemail donation promo the first time a user
tries to rate a transcription. It also changes the good/bad rating links
to thumbs up/down icons.

The 'learn more' link still needs the real URL.

screen shots:
https://drive.google.com/open?id=0B9o_KvtLkcuIOERUNUJId3FVY3UzUS0wVUdQQVpCS1lmM3Nz
https://drive.google.com/open?id=0B9o_KvtLkcuIWkNVMDV1VTJ4VUMtakVwSE1UTGdUWjljTUV3
https://drive.google.com/open?id=0B9o_KvtLkcuIeU1ndG1palRkTnNJQWVYLXgyMnd4TjBDOFI4

mocks:
https://drive.google.com/file/d/1FIhXDkn3h3xI7liVdJEraq47MoKQM3hi/view
https://drive.google.com/file/d/1uTm58QCvFOBycsGP21vgvEGTq_Imgkqi/view

Bug: 37340510
Test: manual tests
PiperOrigin-RevId: 184745497
Change-Id: I40fd1e211311c3127f215ede2e44b22f345dcf8b