KT-14258 Optimize accesses to properties defined into companion

- Use direct access to property defined into companion object when
it is possible rather than always use an accessor to access the
property.
- Use direct access will speedup runtime performance.
- Avoid to generate useless accessors for companion properties.

Fix of https://youtrack.jetbrains.com/issue/KT-14258

compiler/testData/codegen/bytecodeText/companion/kt14258_1.kt

@@ -0,0 +1,16 @@
+// Checks that methods 'access$getMy$p', 'access$getMy$cp' and 'getMy' are not generated and
+// that backed field 'my' is directly used through a 'getstatic'
+
+class My {
+    companion object {
+        private val my: String = "OK"
+    }
+
+    fun getMyValue() = my
+}
+
+// 1 GETSTATIC My.my
+// 1 PUTSTATIC My.my
+// 0 INVOKESTATIC My\$Companion.access\$getMy\$p
+// 0 INVOKESTATIC My.access\$getMy\$cp
+// 0 INVOKESPECIAL My\$Companion.getMy

compiler/testData/codegen/bytecodeText/companion/kt14258_2.kt

@@ -0,0 +1,20 @@
+// Checks that methods 'access$getMy$p' and 'getMy' are not generated and
+// that backed field 'my' is accessed through 'access$getMy$cp'
+
+class My {
+    companion object {
+        private val my: String = "OK"
+
+        fun test(): String {
+            // accessor is required because field is move to Foo
+            return my
+        }
+    }
+
+    fun getMyValue() = test()
+}
+
+// 1 GETSTATIC My.my
+// 0 INVOKESTATIC My\$Companion.access\$getMy\$p
+// 1 INVOKESTATIC My.access\$getMy\$cp
+// 0 INVOKESPECIAL My\$Companion.getMy

compiler/testData/codegen/bytecodeText/companion/kt14258_3.kt

@@ -0,0 +1,28 @@
+// Checks that accessor methods are always used due to the overriding of the default setter of 'my' property.
+
+class My {
+    companion object {
+        private var my: String = "OK"
+            set(value) { field = value }
+    }
+
+    fun getMyValue(): String {
+        // INVOKESTATIC My$Companion.access$setMy$p
+        my = "Overriden value"
+        // GETSTATIC My.my
+        return my
+    }
+
+    // PUTSTATIC My.my into clinit
+    // PUTSTATIC My.my into 'access$setMy$cp'
+    // GETSTATIC My.my into 'access$getMy$cp'
+}
+
+// 2 GETSTATIC My.my
+// 2 PUTSTATIC My.my
+// 0 INVOKESTATIC My\$Companion.access\$getMy\$p
+// 1 INVOKESTATIC My\$Companion.access\$setMy\$p
+// 1 INVOKESTATIC My.access\$setMy\$cp
+// 1 INVOKESTATIC My.access\$getMy\$cp
+// 1 INVOKESPECIAL My\$Companion.getMy
+// 1 INVOKESPECIAL My\$Companion.setMy

compiler/testData/codegen/bytecodeText/companion/kt14258_4.kt

@@ -0,0 +1,23 @@
+// Checks that accessor 'I$Companion.access$getBar\$p' is always used because the property is kept
+// into the companion object.
+
+interface I {
+    companion object {
+        private var bar = "Companion Field from I"
+    }
+
+    fun test(): String {
+        // INVOKESTATIC I$Companion.access$setBar$p
+        bar = "New value"
+        // INVOKESTATIC I$Companion.access$getBar$p
+        return bar
+    }
+}
+
+// 1 GETSTATIC I\$Companion.bar
+// 2 PUTSTATIC I\$Companion.bar
+// 1 INVOKESTATIC I\$Companion.access\$getBar\$p
+// 1 INVOKESTATIC I\$Companion.access\$setBar\$p
+// 0 INVOKESTATIC I\$Companion.access\$setBar\$cp
+// 0 INVOKESPECIAL I\$Companion.getBar
+// 0 INVOKESPECIAL I\$Companion.setBar

compiler/testData/codegen/bytecodeText/companion/kt14258_5.kt

@@ -0,0 +1,19 @@
+// Checks that accessor are not used because property can be accessed directly.
+
+interface I {
+    companion object {
+        private var bar = "Companion Field from I"
+
+        fun test(): String {
+            bar = "New value"
+            return bar
+        }
+    }
+}
+
+// 1 GETSTATIC I\$Companion.bar
+// 2 PUTSTATIC I\$Companion.bar
+// 0 INVOKESTATIC I\$Companion.access\$getBar\$p
+// 0 INVOKESTATIC I\$Companion.access\$setBar\$cp
+// 0 INVOKESPECIAL I\$Companion.getBar
+// 0 INVOKESPECIAL I\$Companion.setBar

compiler/testData/codegen/bytecodeText/constProperty/accessorsForPrivateConstants.kt

@@ -9,9 +9,13 @@ class Foo {
     }
 
     fun foo() {
+        // Access to the property use getstatic on the backed field
         LOCAL_PRIVATE
+        // Access to the property requires an invokestatic
         OUTER_PRIVATE
     }
 }
 
-// 2 INVOKESTATIC
+// 1 INVOKESTATIC
+// 1 PUTSTATIC
+// 2 GETSTATIC

compiler/testData/codegen/bytecodeText/staticFields/classObjectSyntheticAccessor.kt

@@ -1,8 +0,0 @@
-class A {
-    companion object {
-        private var r: Int = 1;
-    }
-}
-// A and companion object constructor call
-// 3 ALOAD 0
-// 1 synthetic access\$getR