[FIR] Add backing fields to const properties during Fir2Ir translation

compiler/testData/codegen/box/binaryOp/overflowChar.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 fun box(): String {
     val c1: Char = Char.MIN_VALUE
     val c2 = c1 - 1

compiler/testData/codegen/box/binaryOp/overflowInt.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 fun box(): String {
     val i1: Int = Int.MAX_VALUE
     val i2 = i1 + 1

compiler/testData/codegen/box/binaryOp/overflowLong.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 fun box(): String {
     val a: Long = 2147483647 + 1
     if (a != -2147483648L) return "fail: in this case we should add to ints and than cast the result to long - overflow expected"