Put default value to vars iff they are not boxed

#KT-24672 Fixed

compiler/testData/codegen/bytecodeText/localInitializationLVT/boxingVar.kt

@@ -0,0 +1,12 @@
+// IGNORE_BACKEND: JVM_IR
+
+fun test(): java.lang.Integer {
+    var c: java.lang.Integer
+    run {
+        c = java.lang.Integer(1)
+    }
+    return c
+}
+
+// 1 ASTORE 0
+// 1 LOCALVARIABLE c Lkotlin/jvm/internal/Ref\$ObjectRef; L1 L11 0

compiler/testData/codegen/bytecodeText/localInitializationLVT/contractVar.kt

@@ -0,0 +1,25 @@
+// IGNORE_BACKEND: JVM_IR
+
+import kotlin.contracts.ExperimentalContracts
+import kotlin.contracts.InvocationKind
+import kotlin.contracts.contract
+
+@ExperimentalContracts
+fun test(): Char {
+    var c: Char
+    doIt {
+        c = ' '
+    }
+    return c
+}
+
+@ExperimentalContracts
+fun doIt(block: () -> Unit) {
+    contract {
+        callsInPlace(block, InvocationKind.EXACTLY_ONCE)
+    }
+    block()
+}
+
+// 0 ISTORE 0
+// 1 LOCALVARIABLE c Lkotlin/jvm/internal/Ref\$CharRef; L1 L3 0

compiler/testData/codegen/bytecodeText/localInitializationLVT/genericsVar.kt

@@ -0,0 +1,18 @@
+// IGNORE_BACKEND: JVM_IR
+
+inline fun <reified T> foo(default: T): T {
+    var t: T
+    run {
+        t = default
+    }
+    return t
+}
+
+fun test() {
+    foo(0.0f)
+}
+
+// two in foo and two in test
+
+// 2 ASTORE 2
+// 1 LOCALVARIABLE t\$iv Lkotlin/jvm/internal/Ref\$ObjectRef; L3 L13 2

compiler/testData/codegen/bytecodeText/localInitializationLVT/ifStatementVar.kt

@@ -0,0 +1,16 @@
+// IGNORE_BACKEND: JVM_IR
+
+import kotlin.random.Random
+
+fun test(): Char {
+    var c: Char
+    if (Random.nextBoolean()) {
+        c = '1'
+    } else {
+        c = '2'
+    }
+    return c
+}
+
+// 3 ISTORE 0
+// 1 LOCALVARIABLE c C L1 L7 0

compiler/testData/codegen/bytecodeText/localInitializationLVT/ifStatementWithoutBlockVar.kt

@@ -0,0 +1,16 @@
+// IGNORE_BACKEND: JVM_IR
+
+import kotlin.random.Random
+
+fun test(): Char {
+    var c: Char
+    if (Random.nextBoolean())
+        c = '1'
+    else
+        c = '2'
+
+    return c
+}
+
+// 3 ISTORE 0
+// 1 LOCALVARIABLE c C L1 L5 0

compiler/testData/codegen/bytecodeText/localInitializationLVT/inlineClassVar.kt

@@ -0,0 +1,12 @@
+// IGNORE_BACKEND: JVM_IR
+
+fun test(): UInt {
+    var c: UInt
+    run {
+        c = 1u
+    }
+    return c
+}
+
+// 1 ASTORE 0
+// 1 LOCALVARIABLE c Lkotlin/jvm/internal/Ref\$IntRef; L1 L11 0

compiler/testData/codegen/bytecodeText/localInitializationLVT/singleBlockVar.kt

@@ -0,0 +1,23 @@
+// IGNORE_BACKEND: JVM_IR
+
+fun test(): Char {
+    var c: Char
+    val l = Any()
+    val l1 = Any()
+    val l2 = Any()
+    val l3 = Any()
+    val l4 = Any()
+    val l5 = Any()
+    val l6 = Any()
+    val l7 = Any()
+    val l8 = Any()
+    val l11 = Any()
+    val l12 = Any()
+    val l13 = Any()
+    val l14 = Any()
+    c = '1'
+    return c
+}
+
+// 2 ISTORE 0
+// 1 LOCALVARIABLE c C L1 L16 0

compiler/testData/codegen/bytecodeText/localInitializationLVT/whenStatementVar.kt

@@ -0,0 +1,22 @@
+// IGNORE_BACKEND: JVM_IR
+
+fun test(i: Int): Char {
+    var c: Char
+    when (i) {
+        1 -> c = '1'
+        2 -> c = '2'
+        3 -> c = '3'
+        4 -> c = '4'
+        5 -> c = '5'
+        6 -> c = '6'
+        7 -> c = '7'
+        8 -> c = '8'
+        9 -> c = '9'
+        0 -> c = '0'
+        else -> c = ' '
+    }
+    return c
+}
+
+// 12 ISTORE 1
+// 1 LOCALVARIABLE c C L1 L16 1