Add flag to change catch variables' default types to unknown (#41013)

* Add test case for 'useUnknownInCatchVariables'.

* Add new 'useUnknownInCatchVariables' flag.

* Accepted baselines.

* Add test for catch variable explicitly typed as 'any'.

* Accepted baselines.

* Move option under 'strict'.

* Accepted baselines.

* 'useUnknownInCatchVariables' is strict in command line help.

src/compiler/commandLineParser.ts

@@ -632,6 +632,15 @@ namespace ts {
             category: Diagnostics.Type_Checking,
             description: Diagnostics.Raise_error_on_this_expressions_with_an_implied_any_type,
         },
+        {
+            name: "useUnknownInCatchVariables",
+            type: "boolean",
+            affectsSemanticDiagnostics: true,
+            strictFlag: true,
+            showInSimplifiedHelpView: true,
+            category: Diagnostics.Type_Checking,
+            description: Diagnostics.Type_catch_clause_variables_as_unknown_instead_of_any,
+        },
         {
             name: "alwaysStrict",
             type: "boolean",