Window splits inside a tab

[Hubro]

This is an intentional duplicate of this closed feature request: #41486

It was closed as a duplicate, but no duplicate issue was linked and through Google or the issues tab I can't for the life of me find that duplicate. If the duplicate still exists and is open, please close this request with a link to the duplicate.

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As somebody who has worked in Vim for years, it seems silly to me that tabs are inside window splits. I would like an option to invert this, so that splits are inside tabs. This will make the Vim mode way, way more like the real thing.

If adding a toggle for this is not viable, then perhaps instead add an API for creating splits inside tabs, and let the Vim mode plugin tap into this API. This wouldn't change the user experience for anybody else.

[bpasero]

/duplicate #36700