Add a feature of Autocompletion

With a click of a **Tab**, aeweb-cli should predict the rest of a word a user is typing.

The issue names aeweb-cli but does not identify files, tests, or a command entry point. First inspect the CLI entry point and current input handling, then determine how Tab-triggered completion should behave. Done means a user can press Tab while typing a word and receive the intended completion, with the behavior covered by an appropriate test.

Written by the indexing model from the issue text.