fixed screen reader output for tooltips, fixes #3962

Closes #3962

Merge request studip/studip!2859

(cherry picked from commit 062a7f9a)

8c8a2717 fixed screen reader output for tooltips
90bb9ad0 removed random bytes generation
de8dea17 changed HTML of tooltips
3889963b added another possibility for tooltip content
93bcc22f removed unnecessary code from bootstrap/tooltip.js
039d1b19 use grid width for tooltips, disabled remaining code in bootstrap/tooltip.js
4ceb886e fixed typo
82479659 fixed errors, removed unused code
be9a55e8 re-formatted scss code
904c374a removed tooltip.js files
30c79de4 removed reference to lib/tooltip.js
c62fe83f removed reference to Tooltip object