Describe the bug
b-form-datepicker and b-form-timepicker in 'button only' mode seem to lack horizontal padding. The issue is present in the official documentation (https://bootstrap-vue.org/docs/components/form-datepicker#button-only-mode):

Expected behavior
The padding should match the non 'button only' mode.
Versions
Libraries:
- BootstrapVue: 2.12.0
- Bootstrap: 4.4.1
- Vue: 2.6.22