[IR] Move IrFactory#createExpressionBody overloads to extension methods

This is to prepare for IrFactory auto-generation (KT-59308).

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/InitializersLowering.kt

@@ -106,9 +106,11 @@ class InitializersCleanupLowering(
             } else {
                 declaration.initializer?.let {
                     declaration.initializer =
-                        context.irFactory.createExpressionBody(it.startOffset, it.endOffset) {
-                            expression = it.expression.deepCopyWithSymbols()
-                        }
+                        context.irFactory.createExpressionBody(
+                            startOffset = it.startOffset,
+                            endOffset = it.endOffset,
+                            expression = it.expression.deepCopyWithSymbols(),
+                        )
                 }
             }
         }

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/InnerClassesLowering.kt

@@ -44,9 +44,11 @@ class InnerClassesLowering(val context: BackendContext, private val innerClasses
             val variableRemapper = VariableRemapper(oldConstructorParameterToNew)
             for ((oldParam, newParam) in oldConstructorParameterToNew.entries) {
                 newParam.defaultValue = oldParam.defaultValue?.let { oldDefault ->
-                    context.irFactory.createExpressionBody(oldDefault.startOffset, oldDefault.endOffset) {
-                        expression = oldDefault.expression.transform(variableRemapper, null).patchDeclarationParents(newConstructor)
-                    }
+                    context.irFactory.createExpressionBody(
+                        startOffset = oldDefault.startOffset,
+                        endOffset = oldDefault.endOffset,
+                        expression = oldDefault.expression.transform(variableRemapper, null).patchDeclarationParents(newConstructor),
+                    )
                 }
             }