Fix warnings and typespec

[dominique-vassard]

A quick PR for:

• fixing 'unused alias' warnings
• Fix Bolt.Sips.Response type which fails for stats
• Add typespec for Node, Relationship which can (will) be useful for projects using bolt_sips

[sourcelevel-bot[bot]]

SourceLevel has finished reviewing this Pull Request and has found:

• 3 possible new issues (including those that may have been commented here).
• 2 fixed issues! 🎉

See more details about this review.

[florinpatrascu]

thank you!