feat: remove userid package from file system adapter

packages/adapter-file-system/README.md

@@ -26,8 +26,6 @@ app.use(
   nepheleServer({
     adapter: new FileSystemAdapter({
       root: '/path/to/webdav/root',
-      // This option is important to get right.
-      usernamesMapToSystemUsers: false,
     }),
     authenticator: new ExampleAuthenticator(),
   })
@@ -41,13 +39,8 @@ app.listen(port, () => {
 # Options / Defaults
 
 - `root`: The absolute path of the directory that acts as the root directory for the service.
-- `usernamesMapToSystemUsers`: Whether the usernames provided by the authenticator map directly to system usernames.
 - `contentEtagMaxMB` = `100`: The maximum filesize in megabytes to calculate etags by a CRC-32C checksum of the file contents.
 
-## usernamesMapToSystemUsers
-
-If this is set to true, and they don't, you **will** see errors. The adapter will attempt to `chown` files to the user who is currently authenticated.
-
 ## contentEtagMaxMB
 
 Anything above this file size will use a CRC-32C checksum of the size, created time, and modified time instead. This will significantly speed up responses to requests for these files, but at the cost of reduced accuracy of etags. A file that has the exact same content, but a different modified time will not be pulled from cache by the client.