remove duplicate content for certain SQL sections under Explore and Analyze

[ketkee-aryamane]

Linked to #2563
This PR removes the following under Explore and Analyze -> SQL and creates redirects to the corresponding reference content. Also updates all referred links to these files with the reference content links.

• SQL Language
• Functions and Operators
• Reserved keywords
• SQL Limitations

[github-actions]

🔍 Preview links for changed docs

• explore-analyze/query-filter/languages/sql-cli.md
• explore-analyze/query-filter/languages/sql-concepts.md
• explore-analyze/query-filter/languages/sql.md
• explore-analyze/visualize/canvas.md

[yetanothertw]

Changes approved.

A suggestion/question: I've recently removed duplicated pages that existed in both the Deploy and manage and Reference sections in favour of the latter. I then added a crosslink to the toc in the Deploy and manage section because it made a lot of sense for the page to be listed in the toc. (It now redirects to the correct, deduplicated page in the Reference section.)
Not sure if this would apply to your use-case, but thought I'd mention it anyway.

[ketkee-aryamane]

Changes approved.

A suggestion/question: I've recently removed duplicated pages that existed in both the Deploy and manage and Reference sections in favour of the latter. I then added a crosslink to the toc in the Deploy and manage section because it made a lot of sense for the page to be listed in the toc. (It now redirects to the correct, deduplicated page in the Reference section.) Not sure if this would apply to your use-case, but thought I'd mention it anyway.

I see! But I think, as per the requirement listed in the issue, this content should only sit in the Reference docs. Good to clear with @florent-leborgne though. Thanks @yetanothertw

[florent-leborgne]

LGTM, thanks @ketkee-aryamane!

[marciw]

LGTM (noted a couple of missing spaces) 🥳