Replace ttyd with etty

## Motivation

[etty](https://github.com/lablup/etty) provides more GUI features, such as tabs and multiple panes like tmux but using the modern web.

It can be also customized to offer Backend.AI-specific integrations.

## Required Features

- Replace `ttyd` with `etty` release binaries (x86_64, aarch64)
- Set up an automated artifact import workflow (just like `all-smi`).
- Apply Backend.AI-specific integrations
- Set the browser’s window/tab title to the Backend.AI session name followed by the current active pane’s title.
- Load/store user configurations (e.g., color theme, fonts) to the [Backend.AI](http://Backend.AI)’s user profiles in the account manager.

##

JIRA Issue: BA-3331