[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 thanks for the reference. Fixed in https://github.com/opf/openproject/commit/787f62d177235304f56f56dd7fdd6f0592c35181.