[clang] [analyzer] Print the callee name in CallEnter in exploded-graph-rewriter (PR #116225)

[Donát Nagy via cfe-commits]

================
@@ -86,6 +86,8 @@ def __init__(self, json_pp):
                 if json_pp["location"] is not None
                 else None
             )
+        elif self.kind == "CallEnter":
+            self.callee_decl = json_pp["callee_decl"] if "callee_decl" in json_pp else "None"
----------------
NagyDonat wrote:

```suggestion
            self.callee_decl = json_pp.get("callee_decl", "None")
```
Assuming that `json_pp` is a plain Python dictionary and not some magical dict-like object that lacks the `get` method.

https://github.com/llvm/llvm-project/pull/116225