Re-organize directory structure (#4971)

See discussion in #2491

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

stdlib/venv/__init__.pyi

@@ -0,0 +1,70 @@
+import sys
+from _typeshed import AnyPath
+from types import SimpleNamespace
+from typing import Optional, Sequence
+
+class EnvBuilder:
+    system_site_packages: bool
+    clear: bool
+    symlinks: bool
+    upgrade: bool
+    with_pip: bool
+    prompt: Optional[str]
+
+    if sys.version_info >= (3, 9):
+        def __init__(
+            self,
+            system_site_packages: bool = ...,
+            clear: bool = ...,
+            symlinks: bool = ...,
+            upgrade: bool = ...,
+            with_pip: bool = ...,
+            prompt: Optional[str] = ...,
+            upgrade_deps: bool = ...,
+        ) -> None: ...
+    else:
+        def __init__(
+            self,
+            system_site_packages: bool = ...,
+            clear: bool = ...,
+            symlinks: bool = ...,
+            upgrade: bool = ...,
+            with_pip: bool = ...,
+            prompt: Optional[str] = ...,
+        ) -> None: ...
+    def create(self, env_dir: AnyPath) -> None: ...
+    def clear_directory(self, path: AnyPath) -> None: ...  # undocumented
+    def ensure_directories(self, env_dir: AnyPath) -> SimpleNamespace: ...
+    def create_configuration(self, context: SimpleNamespace) -> None: ...
+    def symlink_or_copy(self, src: AnyPath, dst: AnyPath, relative_symlinks_ok: bool = ...) -> None: ...  # undocumented
+    def setup_python(self, context: SimpleNamespace) -> None: ...
+    def _setup_pip(self, context: SimpleNamespace) -> None: ...  # undocumented
+    def setup_scripts(self, context: SimpleNamespace) -> None: ...
+    def post_setup(self, context: SimpleNamespace) -> None: ...
+    def replace_variables(self, text: str, context: SimpleNamespace) -> str: ...  # undocumented
+    def install_scripts(self, context: SimpleNamespace, path: str) -> None: ...
+    if sys.version_info >= (3, 9):
+        def upgrade_dependencies(self, context: SimpleNamespace) -> None: ...
+
+if sys.version_info >= (3, 9):
+    def create(
+        env_dir: AnyPath,
+        system_site_packages: bool = ...,
+        clear: bool = ...,
+        symlinks: bool = ...,
+        with_pip: bool = ...,
+        prompt: Optional[str] = ...,
+        upgrade_deps: bool = ...,
+    ) -> None: ...
+
+else:
+    def create(
+        env_dir: AnyPath,
+        system_site_packages: bool = ...,
+        clear: bool = ...,
+        symlinks: bool = ...,
+        with_pip: bool = ...,
+        prompt: Optional[str] = ...,
+    ) -> None: ...
+
+def main(args: Optional[Sequence[str]] = ...) -> None: ...