Improve table views (Sign rules / stored keys)

[lieser]

The current table views in 4.x have a few usability issued, which should be fixed:

• No default minimum/maximum width for the columns
• Simply entering edit mode of a cell can potentially result in a layout change

Additionally, the following would be nice to have (optionally for this issue):

• allow changing the width of the columns
• use a checkbox for bool values
• use a drop down list for the rule type
• use date picker for inserted/last-used date of keys

[lieser]

There also is an issue with the dark Theme that needs to be fixed: The footer with the button is transparent, making the buttons hard to see.

[lieser]

Consider adding a delete all button, or even better allow to selectively delete multiple rows at once.

[lieser]

The layout/styling issues should be fixed in 4.1.0. Usage improvements are still open.

[lieser]

With the switch to the Tabulator library for rendering the tables most improvements should be done. Further improvements will be separately tracked if requested.