Keyboard navigation in memory table

[jreineckearm]

Description

The recently introduced GUI framework comes with capabilities to navigate through the table with the keyboard.
A full navigation strategy need to be defined first. But it could include things like

• Navigating through table cells and groups within Data column cells.
• Initiate editing a group when the functionality is available.
• Selecting groups for subsequent copy.
• Quick navigation up and down with PageUp/PageDown/Home/End/etc keys.

Additional information

In all of this we need to make sure that the navigation agrees with fundamental Visual Studio Code patterns.

[planger]

#140 adressed everything except for quick navigation up and down with PageUp/PageDown/Home/End/etc keys. I updated the issue description.