[clang] [clang][ssaf] Add JSONFormat support for WPASuite (PR #187403)

[Aviral Goel via cfe-commits]

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@@ -0,0 +1,4 @@
+config.substitutions.insert(0,
+    ("%ssaf-format-with-plugin",
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aviralg wrote:

Makes test invocations shorter.

https://github.com/llvm/llvm-project/pull/187403