FIR resolve: add handling of companions as objects

compiler/fir/resolve/testData/resolve/expresssions/companion.kt

@@ -0,0 +1,21 @@
+open class A {
+    companion object {
+        fun foo() {}
+    }
+
+    fun bar() {
+        foo()
+    }
+}
+
+class B {
+    companion object : A() {
+        fun baz() {}
+    }
+}
+
+fun test() {
+    A.foo()
+    B.bar()
+    B.baz()
+}

compiler/fir/resolve/testData/resolve/expresssions/companion.txt

@@ -0,0 +1,42 @@
+FILE: companion.kt
+    public open class A : R|kotlin/Any| {
+        public constructor(): R|A| {
+            super<R|kotlin/Any|>()
+        }
+
+        public final companion object Companion : R|kotlin/Any| {
+            private constructor(): R|A.Companion| {
+                super<R|kotlin/Any|>()
+            }
+
+            public final fun foo(): R|kotlin/Unit| {
+            }
+
+        }
+
+        public final fun bar(): R|kotlin/Unit| {
+            R|/A.Companion.foo|()
+        }
+
+    }
+    public final class B : R|kotlin/Any| {
+        public constructor(): R|B| {
+            super<R|kotlin/Any|>()
+        }
+
+        public final companion object Companion : R|A| {
+            private constructor(): R|B.Companion| {
+                super<R|A|>()
+            }
+
+            public final fun baz(): R|kotlin/Unit| {
+            }
+
+        }
+
+    }
+    public final fun test(): R|kotlin/Unit| {
+        R|/A|.R|/A.Companion.foo|()
+        R|/B|.<Inapplicable(WRONG_RECEIVER): [/A.bar]>#()
+        R|/B|.R|/B.Companion.baz|()
+    }

compiler/fir/resolve/testData/resolve/fromBuilder/enums.txt

@@ -70,7 +70,7 @@ FILE: enums.kt
 
         }
 
-        public final val g: R|kotlin/Double| = <Unresolved name: G>#.<Unresolved name: times>#(R|/Planet.m|).<Unresolved name: div>#(R|/Planet.r|.R|kotlin/Double.times|(R|/Planet.r|))
+        public final val g: R|kotlin/Double| = R|/Planet.Companion.G|.R|kotlin/Double.times|(R|/Planet.m|).R|kotlin/Double.div|(R|/Planet.r|.R|kotlin/Double.times|(R|/Planet.r|))
             public get(): R|kotlin/Double|
 
         public abstract fun sayHello(): R|kotlin/Unit|