In order to be able to deploy the authenticated SENDMEs, these two consensus
parameters are needed to control the minimum version that we can emit and
accept.

See section 4 in prop289 for more details.

Note that at this commit, the functions that return the values aren't used so
compilation fails if warnings are set to errors.

Closes #26842

Signed-off-by: David Goulet <dgoulet@torproject.org>