[FIR] Enable BytecodeText tests for FIR.

143 out of 767 tests (18.6%) are currently failing.

compiler/testData/codegen/bytecodeText/when/exhaustiveWhenUnitStatement.kt

@@ -1,3 +1,4 @@
+// IGNORE_BACKEND_FIR: JVM_IR
 // IGNORE_BACKEND: JVM_IR
 // TODO KT-36840 Don't generate 'throw' clause for statement 'when' in JVM_IR
 

compiler/testData/codegen/bytecodeText/when/integralWhenWithNoInlinedConstants.kt

@@ -1,3 +1,4 @@
+// IGNORE_BACKEND_FIR: JVM_IR
 fun foo1(x: Int): Boolean {
     when(x) {
         0 -> return true

compiler/testData/codegen/bytecodeText/when/switchOptimizationDuplicates.kt

@@ -1,3 +1,4 @@
+// IGNORE_BACKEND_FIR: JVM_IR
 fun foo(x: Int): Int {
     return when (x) {
         1, 1, 2 -> 1001