Description:
This feature request is motivated by the questioner who asked for that feature here:
https://forum.openoffice.org/en/forum/viewtopic.php?t=100859

An example of how this feature is implemented in Microsoft's PowerPoint is shown here: 
https://www.youtube.com/watch?v=eGfwcUYuPNQ

Some points that show the motivation behind this feature and highlight some advantages:
- Getting better control over the presentation: you can better manage your slides and provide an overview of the structure, which is especially useful for larger presentations with more than one topic in it
- It improves the readability of your presentation (during the working process): When slides are organized logically, it makes it easier for you (and colleagues) to work on the presentation as it is logically structured and you can find the section you want to work on more easily and a faster
- Additionally, managing slides within groups/sections allows you to easily apply formatting changes to multiple slides at once. For example, if you want to change the font or color scheme of your presentation, you can do it for multiple slides instead of having to make the same change individually for each slide. This may also be done by creating a new master slide, but sometimes you do not want to create so many master slides

Steps to Reproduce:
Currently, there is no feature that allows you to group slides into sections

Actual Results:
Currently, there is no feature that allows you to group slides into sections

Expected Results:
Slides can be grouped into sections like it can be done in Microsoft PowerPoint


Reproducible: Always


User Profile Reset: No

Additional Info:
Version: 6.4.7.2
Build ID: 1:6.4.7-0ubuntu0.20.04.9
CPU threads: 16; OS: Linux 5.15; UI render: default; VCL: gtk3; 
Locale: en-US (en_US.UTF-8); UI-Language: en-US
Calc: threaded