Parser: Do not produce qualified expressions without receiver in package directives. Add assertion on JetQualifiedExpression

#KT-6907 Fixed

compiler/testData/psi/packages/PackageBlockFirst.txt

@@ -0,0 +1,36 @@
+JetFile: PackageBlockFirst.kt
+  PACKAGE_DIRECTIVE
+    PsiElement(package)('package')
+    PsiWhiteSpace(' ')
+    REFERENCE_EXPRESSION
+      PsiElement(IDENTIFIER)('foobar')
+  PsiWhiteSpace(' ')
+  PsiErrorElement:Expecting a top level declaration
+    PsiElement(LBRACE)('{')
+  PsiWhiteSpace('\n  ')
+  PROPERTY
+    PsiElement(val)('val')
+    PsiWhiteSpace(' ')
+    PsiElement(IDENTIFIER)('a')
+    PsiWhiteSpace(' ')
+    PsiElement(EQ)('=')
+    PsiWhiteSpace(' ')
+    INTEGER_CONSTANT
+      PsiElement(INTEGER_LITERAL)('1')
+  PsiWhiteSpace('\n  ')
+  PROPERTY
+    PsiElement(val)('val')
+    PsiWhiteSpace(' ')
+    PsiElement(IDENTIFIER)('b')
+    PsiWhiteSpace(' ')
+    PsiElement(EQ)('=')
+    PsiWhiteSpace(' ')
+    DOT_QUALIFIED_EXPRESSION
+      REFERENCE_EXPRESSION
+        PsiElement(IDENTIFIER)('foobar')
+      PsiElement(DOT)('.')
+      REFERENCE_EXPRESSION
+        PsiElement(IDENTIFIER)('a')
+  PsiWhiteSpace('\n')
+  PsiErrorElement:Expecting a top level declaration
+    PsiElement(RBRACE)('}')