IR: fix offsets in irTemporary

The variable generated by IrStatementBuilder.irTemporary doesn't inherit
startOffset and endOffset from the builder. In particular, as a result,
temporary variables generated for elvis operator left operand have
UNDEFINED_OFFSET.

Additionally, ProvisionalFunctionExpressionLowering copies the offsets
of a variable to lowered lambda in the variable initializer. With the
problem described above, this causes invalid debug information in
Kotlin/Native, see KT-49360.

Fix irTemporary by using builder's offsets for the variable.

^KT-49360 Fixed

kotlin-native/backend.native/tests/build.gradle

@@ -3180,6 +3180,10 @@ standaloneTest("lambda14") {
     flags = ['-tr']
 }
 
+task lambda_kt49360(type: KonanLocalTest) {
+    source = "codegen/lambda/lambda_kt49360.kt"
+}
+
 task funInterface_implIsNotFunction(type: KonanLocalTest) {
     source = "codegen/funInterface/implIsNotFunction.kt"
 }