[clang] [clang] Add preliminary lifetimebound support to APINotes (PR #114830)

[Saleem Abdulrasool via cfe-commits]

================
@@ -444,6 +454,16 @@ class ParamInfo : public VariableInfo {
     NoEscape = Value.value_or(false);
   }
 
+  std::optional<bool> isLifetimebound() const {
+    if (!LifetimeboundSpecified)
+      return std::nullopt;
+    return Lifetimebound;
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compnerd wrote:

```suggestion
    return LifetimeboundSpecified ? Lifetimebound : std::nullopt;
```

https://github.com/llvm/llvm-project/pull/114830