JVM: add tests for companion object accessor generation

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

@@ -0,0 +1,22 @@
+// !LANGUAGE: +ProperVisibilityForCompanionObjectInstanceField
+// IGNORE_BACKEND: JVM_IR
+// ^ TODO implement ProperVisibilityForCompanionObjectInstanceField feature support in JMV_IR
+
+// FILE: Base.kt
+package a
+
+open class Base {
+    protected companion object {
+        fun foo() = 1
+    }
+}
+
+// FILE: Host.kt
+import a.*
+
+class Host : Base() {
+    fun test() = { foo() }
+}
+
+// @Host.class:
+// 1 synthetic access\$

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

@@ -0,0 +1,20 @@
+// !LANGUAGE: -ProperVisibilityForCompanionObjectInstanceField
+
+// FILE: Base.kt
+package a
+
+open class Base {
+    protected companion object {
+        fun foo() = 1
+    }
+}
+
+// FILE: Host.kt
+import a.*
+
+class Host : Base() {
+    fun test() = { foo() }
+}
+
+// @Host.class:
+// 0 synthetic access\$