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

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/builders/ExpressionHelpers.kt

@@ -45,7 +45,11 @@ fun <T : IrElement> IrStatementsBuilder<T>.irTemporary(
     irType: IrType = value?.type!!, // either value or irType should be supplied at callsite
     isMutable: Boolean = false,
 ): IrVariable {
-    val temporary = scope.createTemporaryVariableDeclaration(irType, nameHint, isMutable)
+    val temporary = scope.createTemporaryVariableDeclaration(
+        irType, nameHint, isMutable,
+        startOffset = startOffset,
+        endOffset = endOffset
+    )
     value?.let { temporary.initializer = it }
     +temporary
     return temporary