Re-organize directory structure (#4971)

See discussion in #2491

Co-authored-by: Ivan Levkivskyi <ilevkivskyi@dropbox.com>

stdlib/mimetypes.pyi

@@ -0,0 +1,36 @@
+import sys
+from typing import IO, Dict, List, Optional, Sequence, Text, Tuple, Union
+
+if sys.version_info >= (3, 8):
+    from os import PathLike
+    def guess_type(url: Union[Text, PathLike[str]], strict: bool = ...) -> Tuple[Optional[str], Optional[str]]: ...
+
+else:
+    def guess_type(url: Text, strict: bool = ...) -> Tuple[Optional[str], Optional[str]]: ...
+
+def guess_all_extensions(type: str, strict: bool = ...) -> List[str]: ...
+def guess_extension(type: str, strict: bool = ...) -> Optional[str]: ...
+def init(files: Optional[Sequence[str]] = ...) -> None: ...
+def read_mime_types(filename: str) -> Optional[Dict[str, str]]: ...
+def add_type(type: str, ext: str, strict: bool = ...) -> None: ...
+
+inited: bool
+knownfiles: List[str]
+suffix_map: Dict[str, str]
+encodings_map: Dict[str, str]
+types_map: Dict[str, str]
+common_types: Dict[str, str]
+
+class MimeTypes:
+    suffix_map: Dict[str, str]
+    encodings_map: Dict[str, str]
+    types_map: Tuple[Dict[str, str], Dict[str, str]]
+    types_map_inv: Tuple[Dict[str, str], Dict[str, str]]
+    def __init__(self, filenames: Tuple[str, ...] = ..., strict: bool = ...) -> None: ...
+    def guess_extension(self, type: str, strict: bool = ...) -> Optional[str]: ...
+    def guess_type(self, url: str, strict: bool = ...) -> Tuple[Optional[str], Optional[str]]: ...
+    def guess_all_extensions(self, type: str, strict: bool = ...) -> List[str]: ...
+    def read(self, filename: str, strict: bool = ...) -> None: ...
+    def readfp(self, fp: IO[str], strict: bool = ...) -> None: ...
+    if sys.platform == "win32":
+        def read_windows_registry(self, strict: bool = ...) -> None: ...