Multiple improvements for the manager

[Senyoret1]

Did you run make format && make check?
The go code was not changed. npm run lint and npm run build were used.

Changes:

• Now the tables can be sorted by element label.
• The "ascending" and "descending" texts shown to indicate how the data is sorted were changed to normal and inverted mode, as the previous texts were not always correct, due to the way in which some columns are sorted.
• Some additional help messages were added.
• A problem with the color of disabled buttons in front of the dark background was solved. Also, the code of the button component was cleaned.
• The design of the filter list was polished a bit.
• Now the user is asked for confirmation before logging out.
• Some improvements to the responsive design.

How to test this PR:
Just use the manager normally and check the changes in the list.