Replace `react-bootstrap-table` and `react-bootstrap-button-loader`
- Replace
react-bootstrap-table
with ``react-bootstrap-table-next` - see #371 - Remove
react-bootstrap-button-loader
altogether (just disable the button and change its label instead) - see !391 (comment 86919) - the library is not very well maintained; if we decide we need spinner on buttons later on, we can always create this very simple component ourselves.