Add optional info-message and discussion-message configs

These the over-ride info-link and discussion-link configs respectively
with a localisable message. Also remove the requirement for info-link
and discussion-link to be supplied, as the logic to XOR require -link
or -msg is a pain and this is triviably circumventable by setting to
false.

Bug: 54788
Change-Id: Iccf52b789682d04bd5c4539e5bbb227e0b72ebc2
Merge "Add optional info-message and discussion-message configs"