delete abstract method
Deletes this FileSystemEntity.
If the FileSystemEntity is a directory, and if recursive is false,
the directory must be empty. Otherwise, if recursive is true, the
directory and all sub-directories and files in the directories are
deleted. Links are not followed when deleting recursively. Only the link
is deleted, not its target.
If recursive is true, the FileSystemEntity is deleted even if the type
of the FileSystemEntity doesn't match the content of the file system.
This behavior allows delete to be used to unconditionally delete any file
system object.
Returns a `Future<FileSystemEntity>` that completes with this
FileSystemEntity when the deletion is done. If the FileSystemEntity
cannot be deleted, the future completes with an exception.
Implementation
Future<FileSystemEntity> delete({bool recursive = false});