Volunteer Portal - Admin creates time windows

[dherbst]

Feature Description

Admin users can create time windows that specify:

• Date/time and duration of the volunteer window which is a contiguous block of time (e.g. 9am-5pm)
• How many volunteers are needed to fill the window (2+, etc) (this is the ideal number of volunteers) unlimited after the target number

Expected solution

Use the vue-datepicker on the create page

The "+" button on the admin calendar goes to the create page

Testing

[dherbst]

Updated requirements from the 4/10/23 meeting.