DialogsAddTable/Courses: indicate when no courses are available

[Mutugiii]

Could we replicate a fix like this that fixes #6622 in the courses dialog table as well?

Also, we could replicate the same fix on other dialogs like in teams, we have add resources as well

[paulbert]

Looks like that has already been implemented for Resources & Courses. Closing.

[paulbert]

Misunderstood. This is asking if we should add the message when there are resources or courses available, but the search text doesn't match any of them.

I think we may need to use something other than *ngIf to hide the table instead of destroying it or maybe there's an option on *ngIf for this.