Start: Ability to customize Start page (existed when Start was a workbench)

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Problem description

Since the Start Page is not a workbench anymore there is no possibility to customize it through preferences.

It would be great if the customization options that were there before (see [here](https://wiki.freecad.org/Start_Preferences/en)) came back:


Not showing the examples folder on every startup would be a nice setting to have but also showing the contents of a custom folder.
Alternatively setting the parameter under `Base app -> Preferences -> Mod -> Start -> ShowExamples = false` should affect the actual behaviour of the Start Page.
Setting the parameter `Base app -> Preferences -> Mod -> Start -> ShowOnStartup = false` does result in showing or not showing the Start Page which I would consider inconsistent behaviour of the parameters.

### Full version info

```shell
OS: Nobara Linux 41 (KDE Plasma) (KDE/plasma/xcb)
Architecture: x86_64
Version: 1.0.0.39109 (Git) Conda AppImage
Build type: Release
Branch: (HEAD detached at 1.0.0)
Hash: 2fcc5317fe3aee96ca73475986a577719fc78e20
Python 3.11.9, Qt 5.15.13, Coin 4.0.3, Vtk 9.2.6, OCC 7.7.2
Locale: German/Germany (de_DE)
Stylesheet/Theme/QtStyle: FreeCAD Dark.qss/FreeCAD Dark/Fusion
Installed mods:
* btl 0.9.9
* SearchBar 1.0.2
* Manipulator 1.5.7
* Curves 0.6.52
```

### Subproject(s) affected?

None

### Anything else?

_No response_

### Code of Conduct

- [x] I agree to follow this project's Code of Conduct