feat(structs): add FilterStructToMap utility function

[hanXen]

Resolves #673

Summary

This PR introduces FilterStructToMap, a utility function in the structs package that converts a struct into a map[string]any while respecting json tags, omitempty, and user-defined field filters.

This is a direct solution to the problem identified in naabu#1545, where the existing FilterStruct utility caused issues with JSON marshaling due to its zero-value filtering approach.

Implementation Details

• FilterStructToMap[T any](...) (map[string]any, error):

  • Takes a struct and include/exclude field lists as input.
  • Iterates through struct fields using reflect.
  • Uses the json tag as the key for the output map.
  • Skips zero-valued fields when omitempty is present.
  • Respects the include/exclude lists for filtering.
  • Returns a clean map for JSON marshaling.

• walkFilteredFields (Internal Helper):

  • To avoid code duplication, a new internal helper function, walkFilteredFields, has been created.
  • This function encapsulates the common logic of iterating through fields while checking against the include/exclude maps.
  • Refactored FilterStruct to reuse the same logic, reducing duplication.

This utility offers a reliable, reusable solution for JSON-safe struct filtering and serialization.

[Mzack9999]

LGTM!