Fir2Ir: enable IR-based fake override builder

Invert the logic of IR/FIR2IR-based generators: change the CLI argument
to -Xuse-fir-fake-override-builder, test directive to
USE_FIR_BASED_FAKE_OVERRIDE_GENERATOR, etc.

The changes in test data caused by using IR fake override builder by
default are in the subsequent commit.

 #KT-61514

compiler/cli/cli-common/gen/org/jetbrains/kotlin/cli/common/arguments/CommonCompilerArgumentsCopyGenerated.kt

@@ -75,9 +75,9 @@ fun copyCommonCompilerArguments(from: CommonCompilerArguments, to: CommonCompile
     to.unrestrictedBuilderInference = from.unrestrictedBuilderInference
     to.useExperimental = from.useExperimental?.copyOf()
     to.useFirExtendedCheckers = from.useFirExtendedCheckers
+    to.useFirFakeOverrideBuilder = from.useFirFakeOverrideBuilder
     to.useFirIC = from.useFirIC
     to.useFirLT = from.useFirLT
-    to.useIrFakeOverrideBuilder = from.useIrFakeOverrideBuilder
     to.useK2 = from.useK2
     to.verbosePhases = from.verbosePhases?.copyOf()
 

compiler/cli/cli-common/gen/org/jetbrains/kotlin/cli/common/arguments/K2JVMCompilerArgumentsCopyGenerated.kt

@@ -88,4 +88,4 @@ fun copyK2JVMCompilerArguments(from: K2JVMCompilerArguments, to: K2JVMCompilerAr
     to.valueClasses = from.valueClasses
 
     return to
-}
+}

compiler/cli/cli-common/src/org/jetbrains/kotlin/cli/common/arguments/CommonCompilerArguments.kt

@@ -503,10 +503,10 @@ They should be a subset of sources passed as free arguments."""
         }
 
     @Argument(
-        value = "-Xuse-ir-fake-override-builder",
-        description = "Generate fake overrides via IR. See KT-61514"
+        value = "-Xuse-fir-fake-override-builder",
+        description = "Generate all fake overrides via FIR2IR instead of IR, i.e. revert to behavior before KT-61514 was resolved."
     )
-    var useIrFakeOverrideBuilder = false
+    var useFirFakeOverrideBuilder = false
         set(value) {
             checkFrozen()
             field = value