pkg/bindings: Add tests for ToParams and helpers

[ROKUMATE]

Fixes: #28930

What

Add unit tests for pkg/bindings/internal/util: ToParams, Changed,
IsSimpleType, and SimpleTypeToParam. These had no test coverage.

Why

ToParams builds the URL query parameters for every binding call, so its
behavior matters broadly and is easy to regress: only non-nil fields are
emitted, the schema tag renames a param (and - omits it), simple types and
fmt.Stringer become a single value, slices become repeated values, and maps
are serialized to JSON. The tests lock this in.

Details

Table-driven tests in pkg/bindings/internal/util/util_test.go covering:

• IsSimpleType / SimpleTypeToParam for bool/int/uint/string/Stringer and
  non-simple types
• Changed for set vs nil fields
• ToParams: nil/typed-nil input, unset fields skipped, simple fields, slices,
  maps (JSON), schema-tag rename and "-" omission, and the slice-of-non-simple
  error path

No production code changes. go test ./pkg/bindings/internal/util/ passes.

[TomSweeneyRedHat]

LGTM, assuming happy tests

[ROKUMATE]

acc. to me the failing tests are not related to the pr i made as the pr aims for adding unit-test file (no production code change) and all unit jobs passed which are related to it ...