feat: add how to install DL using TF guide

Description

This MR introduces "How to install Database Lab using Terraform" guide and related structure and material changes.

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Checklist

• the MR description has been reviewed
• this MR contains text changes and they have been reviewed OR there are no texts changes
• this MR contains GUI/CLI changes and they have been reviewed OR there are no GUI/CLI changes
• this MR contains API changes and they have been reviewed OR there are no API changes