Add dongtai logo

Purpose

Add a dongtai logo to create a DongTai IAST project template into built-in project templates, see details in this issue https://gitlab.com/gitlab-jh/gitlab-jh-enablement/-/issues/168, and related MR gitlab!81758 (closed)

Screenshots

Checklist

For a new icon and/or illustration:

• Link to related design issue:
• If this adds an icon ensure that it follows the new icon checklists.
• If this adds an illustration ensure that it follows the new illustration checklists.

For third-party trademarks:

• If this adds or updates an icon or illustration that includes a third-party trademark, ensure that it follows the process for adding third-party trademarks to GitLab.