BBB plugin: add option to hide previous recordings
When using the videoconference plugin (BBB), if recording a lot of conferences (and possibly not all are recorded), the list shown to students is very long, which might confuse them.
Add an option to "hide" a previous conference. This might require the addition of a field in the plugin_bbb_recording table.
Add possibility to hide recordings to students in conferences list in BBB plugin - refs #7324