Describe the bug

For now, libraries can set an exceptional open or closed days but cannot set an open period.
The opened period option is missing. Ex: open every day during the exams session.

To Reproduce

1. Go to 'My library'
2. Add an exception for a period of time.

Expected behavior

There should be the same option for the day and for the period: open and closed.

Context

• server: ils.test.rero.ch or ilsdev.test.rero.ch?
• version: v1.6.1 or the commit hash (see frontpage).
• browser: [if relevant, e.g. chrome, safari, version 78].

Screenshots

For the day

For the period

Additional context