Handle byte-path Jsonnet imports to prevent apply-time provisioning failures

[Copilot]

Otterdog could report The changes could not be applied successfully due to a Jsonnet evaluator type error (bytes passed where str was expected) during apply/provisioning, while the PR was already merged. This change removes that runtime type mismatch in the Jsonnet import callback path.

• Root-cause fix: normalize callback inputs before path resolution

  • Updated otterdog.utils._make_jsonnet_import_callback(...) to accept str | bytes for callback args and normalize via os.fsdecode(...).
  • Ensures downstream path operations and callback return values stay string-based for rjsonnet/Python interop.

• Regression coverage

  • Added test_jsonnet_import_callback_accepts_byte_paths in tests/test_utils.py.
  • Validates the callback works when invoked with byte-based base/rel inputs and still resolves/returns expected content.

def callback(base: str | bytes, rel: str | bytes) -> tuple[str, str | None]:
    base = os.fsdecode(base)
    rel = os.fsdecode(rel)
    candidate = rel if os.path.isabs(rel) else os.path.join(base, rel)
    ...