Duplicate passkey icon (third_party_logos and sprite_icons)

Purpose

Currently the passkey icon is in the third_party_logos folder. I propose to be included additionally into the sprite_icons for easy use in buttons.

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.