review: new and changed commands

[toofar]

There are several new and changed commands. We should review them to see if they are all needed, any suggestions for name or option changes, merging with existing commands.

Some examples:

• :tree-tab-create-group could be used independently of tree tabs, similar to about:blank with with an adjustable title. A related discussion happened here: qutebrowser internal pages should respect colors.webpage.preferred_color_scheme #8054 and @arza-zara suggests making it an option to :open here: Implement Tree Tabs #4602 (comment) it could also grow into something like tab groups / tagging of tabs #49 (comment)
• :tree-tab-suspend-children as above, this could be independent of tree tabs. It uses the existing qute://back mechanism. Which would work with any tab, a --recursive option would handle the tree groups case (also mentioned on the old PR Implement Tree Tabs #4602 (comment))
• should open --sibling|--related imply --tab|--background?
• demote doesn't take a count, promote does, shouldn't they both? (some discussion of counts on the PR already Implement Tree Tabs #4602 (comment))
• tab-clone creates a related tab, should it be sibling?
• is the tree- prefix useful for the new commands? Dropping that is also brought up here: Implement Tree Tabs #4602 (comment)
• do we want --hide, --show, --recursive args to :tree-tab-toggle-hide? The first to not to toggle but just to unambiguous set the visibility, the third on uncollapse any collapsed child groups too
• on that note, how about a --cycle arg to :tree-tab-toggle-hide and then get rid of :tree-tab-cycle-hide?