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_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