fix(1996): Implement register method enum converter

[rubenspeculis]

Added a new function RegisterMethodToV1Enum() to Node, converting the internal register method string to the corresponding V1 Enum value. Included corresponding unit test in node_test.go to ensure correct conversion for various register methods.

• have read the CONTRIBUTING.md file
• raised a GitHub issue or discussed it on the projects chat beforehand
• added unit tests
• added integration tests
• updated documentation if needed
• updated CHANGELOG.md

[kradalby]

Fixes #1996