Create pygments stubs (#5759)

* run stubgen

* replace individual lexers with __getattr__ in lexers/__init__.pyi

* replace individual styles with __getattr__ in styles/__init__.pyi

* import-export each formatter into formatters/__init__.pyi

* clean up slightly with quick and dirty script

* manual fixing

stubs/Pygments/@tests/requirements-stubtest.txt

@@ -0,0 +1 @@
+sphinx

stubs/Pygments/@tests/stubtest_allowlist.txt

@@ -0,0 +1,12 @@
+# Pygments uses mcs, pyright wants cls
+pygments.lexer.LexerMeta.__new__
+pygments.style.StyleMeta.__new__
+
+# Defined in lexer classes, intended to be used as static method, but doesn't use @staticmethod
+pygments.lexer.LexerMeta.analyse_text
+
+# Inheriting from tuple seems to do something weird
+pygments.token.Number
+pygments.token.String
+pygments.token.Token
+pygments.token.Whitespace