docs: add the carla simulator page under digital twin

[evshary]

Description

Add the Carla simulator page, which includes several projects able to bridge Autoware and Carla.

Pre-review checklist for the PR author

The PR author must check the checkboxes below when creating the PR.

• I've confirmed the contribution guidelines.
• The PR follows the pull request guidelines.

In-review checklist for the PR reviewers

The Reviewers must check the checkboxes below before approval.

• The PR follows the pull request guidelines.

Post-review checklist for the PR author

The PR author must check the checkboxes below before merging.

• There are no open discussions or they are tracked via tickets.

After all checkboxes are checked, anyone who has write access can merge the PR.

[evshary]

Before merging the PR, I'll ask the community to add more projects to the pages.

[evshary]

I have asked for permission to put other projects on the page.
https://github.com/orgs/autowarefoundation/discussions/3391#discussioncomment-8391628
https://github.com/orgs/autowarefoundation/discussions/2828#discussioncomment-8408457
I think it's ready for review now.

[github-actions]

Documentation URL: https://autowarefoundation.github.io/autoware-documentation/pr-517/
Modified URLs:

• https://autowarefoundation.github.io/autoware-documentation/pr-517/tutorials/ad-hoc-simulation/digital-twin-simulation/carla-tutorial/

[evshary]

Hi @mitsudome-r
It would be great if you could take a look at the changes.
Please let me know if you have any comments. Thank you.

[mitsudome-r]

LGTM!