This switch moves to a full AWS stack and a core ssl library with
smaller security attack surface. It increases final binary size by
3MB which may be largely avoided by tweaking the aws-lc build
commands at the expense of some performance. Note aws-lc will
likely be the primarily supported ssl library by the AWS c
runtime libs moving forward, and thus this also allows us to move
to more recent versions of the dependant libraries. We still
require a custom fork of aws-c-cal until PR 89 is merged
