Support bool/int/string_list attribute values in the target graph mapper

[yushan8]

Summary

Intent:

• Tango's OptimizedTarget.Attributes only ever carried string-valued Bazel
  rule attributes: mapper.go filtered ingestion to Attribute_STRING and
  dropped every other type, so a target whose only real change was e.g. a
  boolean or integer attribute flip was still flagged as changed (via the
  target hash) but got misclassified during finer-grained diffing since the
  attribute-equality check never saw the change.

Changes:

• Replaced the STRING-only filter in mapper.ResultToTargetGraph with
  attributeValue, which stringifies STRING, BOOLEAN, INTEGER, and
  STRING_LIST typed attributes into the existing string value intern table.
• STRING_LIST values are sorted before encoding, matching the existing
  precedent in core/targethasher/sourcehasher.go's encodeAttribute (which
  sorts string_list_value for the same reason: Bazel query does not
  guarantee stable list ordering across runs when nothing semantically
  changed). Values are JSON-encoded rather than delimiter-joined so
  elements containing arbitrary characters can't collide.
• Other collection/dict/label attribute types (STRING_DICT, LABEL_LIST,
  INTEGER_LIST, etc.) are still dropped rather than stringified, since a
  naive string join isn't safe for them without a canonical encoder.

---

_{Generated by the 🪄 pr-create skill in devexp-agent-marketplace}

Test Plan

Issues