mgt-agenda should show something ('no meeting') when there's no data

[beth-panx]

Describe the bug When a new user is trying out mgt-agenda. Because there's no meeting in user's calendar, canvas will remain blank. This will confuse developer whether their code worked.

To Reproduce Steps to reproduce the behavior:

1. Have a new tenant with a user that has no meetings
2. Add mgt-agenda to app
3. See screen with nothing...

Expected behavior We should have some placeholder wording if no meeting is retrieved.

[msftbot[bot]]

Hello beth-panx, thank you for opening an issue with us!

I have automatically added a "needs triage" label to help get things started. Our team will analyze and investigate the issue, and escalate it to the relevant team if possible. Other community members may also look into the issue and provide feedback 🙌

[tramadon]

ic_no_meetings_today.svg.zip