New docs: Opentofu

[5long]

Add docs for OpenTofu: a fork of Terraform since upstream changed its license to BUSL.

The current Terraform docs is out-of-date (#2590). OpenTofu can serve as a decently compatible replacement (see https://cani.tf). Some might argue that it's preferred than the upstream due to community-driven development.

If you’re adding a new scraper, please ensure that you have:

• Tested the scraper on a local copy of DevDocs
• Ensured that the docs are styled similarly to other docs on DevDocs

• Added these files to the public/icons/your_scraper_name/ directory:
  • 16.png: a 16×16 pixel icon for the doc
  • 16@2x.png: a 32×32 pixel icon for the doc
  • SOURCE: A text file containing the URL to the page the image can be found on or the URL of the original image itself

Known Issue

At least one page http://localhost:9292/opentofu~1.11/cli/config/environment-variables/index is truncated at around TF_LOG_PATH for no apparent reason. Upstream page is fairly big -- the raw HTML is 98k. However, there are bigger pages (e.g. http://localhost:9292/opentofu~1.11/language/settings/backends/s3/index , 104k HTML) that doesn't get truncated. I'm still trying to figure out why. But I guess imperfect docs is better than no docs at all.

Misc

• Only officially support versions 1.9 ~ 1.11 are included & tested. Unsupported versions 1.6 ~ 1.8 can be found on opentofu.org which can be added if needed.
• To keep things simple, the code treats Opentofu as a single word without having to capitalize t.