(PUP-2557) Issue deprecation warning for AST::Node inheritance

Puppet.deprecation_warning constructs an internal stack trace and is
mostly useful for internal deprecation notices as opposed to notices of
deprecation in Puppet manifests. Because of this, a regular warning was
being used in its place for the node inheritance deprecation. But this
would bypass limits on deprecation warnings and the ability to suppress
deprecation warnings added in PUP-2650.

This commit adds a puppet_deprecation_warning() which shares code now
with deprecation_warning, and which traces to the file and line of the
node's context. The AST::Node inheritance warning uses this method now.