Parser: group internal methods into a class

Replicates graphql/graphql-js@7de6d85

Author: Cito

src/graphql/language/lexer.py

@@ -63,22 +63,11 @@ class Lexer:
     EOF token whenever called.
     """
 
-    def __init__(
-        self,
-        source: Source,
-        no_location=False,
-        experimental_fragment_variables=False,
-        experimental_variable_definition_directives=False,
-    ) -> None:
+    def __init__(self, source: Source) -> None:
         """Given a Source object, this returns a Lexer for that source."""
         self.source = source
         self.token = self.last_token = Token(TokenKind.SOF, 0, 0, 0, 0)
         self.line, self.line_start = 1, 0
-        self.no_location = no_location
-        self.experimental_fragment_variables = experimental_fragment_variables
-        self.experimental_variable_definition_directives = (
-            experimental_variable_definition_directives
-        )
 
     def advance(self) -> Token:
         self.last_token = self.token