Move standard-json "modelCheckerSettings" key to "settings.modelChecker".

test/cmdlineTests/standard_model_checker_timeout_all/input.json

@@ -7,8 +7,11 @@
 			"content": "// SPDX-License-Identifier: GPL-3.0\npragma solidity >=0.0;\npragma experimental SMTChecker;\ncontract test {\nfunction f(uint x, uint y, uint k) public pure {\nrequire(k > 0); require(x % k == 0); require(y % k == 0); uint r = mulmod(x, y, k); assert(r % k == 0);}}"
 		}
 	},
-	"modelCheckerSettings":
+	"settings":
 	{
-		"timeout": 1000
+		"modelChecker":
+		{
+			"timeout": 1000
+		}
 	}
 }