[stubs] fix cls stubs for declarations with context receivers

^KTIJ-21243 fixed

analysis/decompiled/decompiler-to-file-stubs/testData/clsFileStubBuilder/ContextReceiversOnClass/ContextReceiversOnClass.kt

@@ -0,0 +1,14 @@
+// !LANGUAGE: +ContextReceivers
+
+context(A, B)
+private open class ContextReceiversOnClass {
+
+}
+
+class A {
+    val valueA: Int = 10
+}
+
+class B {
+    val valueB: Int = 11
+}

analysis/decompiled/decompiler-to-file-stubs/testData/clsFileStubBuilder/ContextReceiversOnClass/ContextReceiversOnClass.txt

@@ -0,0 +1,18 @@
+PsiJetFileStubImpl[package=]
+  PACKAGE_DIRECTIVE
+  IMPORT_LIST
+  CLASS[classId=/ContextReceiversOnClass, fqName=ContextReceiversOnClass, isEnumEntry=false, isInterface=false, isLocal=false, isTopLevel=true, name=ContextReceiversOnClass, superNames=[]]
+    CONTEXT_RECEIVER_LIST
+      CONTEXT_RECEIVER
+        TYPE_REFERENCE
+          USER_TYPE
+            REFERENCE_EXPRESSION[referencedName=A]
+      CONTEXT_RECEIVER
+        TYPE_REFERENCE
+          USER_TYPE
+            REFERENCE_EXPRESSION[referencedName=B]
+    MODIFIER_LIST[open private]
+    PRIMARY_CONSTRUCTOR
+      MODIFIER_LIST[public]
+      VALUE_PARAMETER_LIST
+    CLASS_BODY