improve parser recovery if keyword is used as function or class name (PY-8319)

python/testData/psi/KeywordAsClassName.py

@@ -0,0 +1,2 @@
+class from:
+    pass

python/testData/psi/KeywordAsClassName.txt

@@ -0,0 +1,13 @@
+PyFile:KeywordAsClassName.py
+  PyClass: null
+    PsiElement(Py:CLASS_KEYWORD)('class')
+    PsiWhiteSpace(' ')
+    PsiErrorElement:Identifier expected
+      PsiElement(Py:FROM_KEYWORD)('from')
+    PyArgumentList
+      <empty list>
+    PsiElement(Py:COLON)(':')
+    PsiWhiteSpace('\n    ')
+    PyStatementList
+      PyPassStatement
+        PsiElement(Py:PASS_KEYWORD)('pass')

python/testData/psi/KeywordAsFunctionName.py

@@ -0,0 +1,2 @@
+def from():
+    pass

python/testData/psi/KeywordAsFunctionName.txt

@@ -0,0 +1,14 @@
+PyFile:KeywordAsFunctionName.py
+  PyFunction('null')
+    PsiElement(Py:DEF_KEYWORD)('def')
+    PsiWhiteSpace(' ')
+    PsiErrorElement:function name expected
+      PsiElement(Py:FROM_KEYWORD)('from')
+    PyParameterList
+      PsiElement(Py:LPAR)('(')
+      PsiElement(Py:RPAR)(')')
+    PsiElement(Py:COLON)(':')
+    PsiWhiteSpace('\n    ')
+    PyStatementList
+      PyPassStatement
+        PsiElement(Py:PASS_KEYWORD)('pass')