[Feature] 8720 toolbar at bottom of details view

[``* `#8720` Toolbar at bottom detail view``](https://www.openproject.org/work_packages/8720)

:exclamation: https://github.com/finnlabs/openproject-costs/pull/104
@myabc it is a typo. Thanks for the hint! Fixed in https://github.com/opf/openproject/commit/6529defe85d20d35e60bb4382ba23a81b8eb8f9b.