feat: add `Context.setConfig`

src/Lean/Meta/Tactic/Simp/Types.lean

diff --git a/src/Lean/Meta/Tactic/Simp/Types.lean b/src/Lean/Meta/Tactic/Simp/Types.lean
index 5eb059f..87f538c 100644
--- a/src/Lean/Meta/Tactic/Simp/Types.lean
+++ b/src/Lean/Meta/Tactic/Simp/Types.lean
@@ -121,6 +121,9 @@
   let config ← updateArith config
   return { config, simpTheorems, congrTheorems }
 
+def Context.setConfig (context : Context) (config : Config) : Context :=
+  { context with config }
+
 def Context.setSimpTheorems (c : Context) (simpTheorems : SimpTheoremsArray) : Context :=
   { c with simpTheorems }