Refactor ns device registry validation

[halimi]

Summary

References: #7380

The NsEndDeviceRegistryServer.Set() function is more than 3k row long and it is hard to follow what it does. The biggest part is doing different kind of validations and this part can be split up and move out to different validator functions.

Changes

• Split up the NsEndDeviceRegistryServer.Set() function validation part and move it out to validator functions.

Testing

Steps

The code logic haven't changed just restructured. The unit tests should pass.

Results

Regressions

Notes for Reviewers

The code logic haven't changed just moved out some part of the code to validator functions. This change will make it easier to validate the mac setting profile.

Checklist

• Scope: The referenced issue is addressed, there are no unrelated changes.
• Compatibility: The changes are backwards compatible with existing API, storage, configuration and CLI, according to the compatibility commitments in README.md for the chosen target branch.
• Documentation: Relevant documentation is added or updated.
• Testing: The steps/process to test this feature are clearly explained including testing for regressions.
• Infrastructure: If infrastructural changes (e.g., new RPC, configuration) are needed, a separate issue is created in the infrastructural repositories.
• Changelog: Significant features, behavior changes, deprecations and fixes are added to CHANGELOG.md.
• Commits: Commit messages follow guidelines in CONTRIBUTING.md, there are no fixup commits left.