[ #HLODiff ] Refine computation diff.

- Add color decoration for unmatched/changed instructions.
- Support unmatched computation
- Update text to summarize diff pattern
- Show the sample diff by default

PiperOrigin-RevId: 780203634

Author: d4n1elchen

third_party/xla/xla/hlo/tools/hlo_diff/render/BUILD

@@ -73,6 +73,7 @@ cc_library(
         "@com_google_absl//absl/container:flat_hash_map",
         "@com_google_absl//absl/container:flat_hash_set",
         "@com_google_absl//absl/functional:function_ref",
+        "@com_google_absl//absl/log:check",
         "@com_google_absl//absl/status:statusor",
         "@com_google_absl//absl/strings",
         "@com_google_absl//absl/strings:str_format",