MINOR: version: report the version status in "haproxy -v"

MINOR: version: report the version status in "haproxy -v"

As discussed on Discourse here:

    https://discourse.haproxy.org/t/haproxy-branch-support-lifetime/4466

it's not always easy for end users to know the lifecycle of the version
they are using. This patch introduces a "Status" line in the output of
"haproxy -vv" indicating whether it's a development, stable, long-term
supported version, possibly with an estimated end of life for the branch
when it can be anticipated (e.g. for stable versions). This field should
be adjusted when creating a major release to reflect the new status.

It may make sense to backport this to other branches to clarify the
situation.