FIR2IR: avoid descriptors computing hashCode

When synthesizing the hashCode function for data classes, descriptors
were used, in partcular, memberScope for primitive classes.
IrBasedDescriptors have no member scope, so we compute the hashCode
function based on IR structures.

compiler/testData/codegen/bytecodeText/inlineClasses/inlineClassInGeneratedToString.kt

@@ -1,5 +1,4 @@
 // !LANGUAGE: +InlineClasses
-// IGNORE_BACKEND_FIR: JVM_IR
 
 // FILE: Z.kt
 inline class Z(val value: Int)