[ty] Improve diagnostics for unsupported binary operations and unsupported augmented assignments (#21947)

## Summary

This PR takes the improvements we made to unsupported-comparison
diagnostics in https://github.com/astral-sh/ruff/pull/21737, and extends
them to other `unsupported-operator` diagnostics.

## Test Plan

Mdtests and snapshots

crates/ty_python_semantic/resources/mdtest/assignment/augmented.md

@@ -38,6 +38,8 @@ reveal_type(x)  # revealed: int
 
 ## Unsupported types
 
+<!-- snapshot-diagnostics -->
+
 ```py
 class C:
     def __isub__(self, other: str) -> int: