Show Add Students CTA when there are no students on the course

[merkushin]

Fixes part of #4958

Changes proposed in this Pull Request

• Display Add Students button if a course is selected, but no students found.

Testing instructions

• Create a new course.
• Go to Students.
• Select your new course in Filter By Course and apply filter.
• You see Add Students button.

Screenshot / Video

[merkushin]

@Luchadores
I wasn't sure what should I do on the click by the Add Students button.
I decided to send the user to the following screen:

Is that correct behavior?

[Luchadores]

@merkushin 👋

I would say it's perfect for now. In the future, we will introduce a new way of adding students. Until then, this should be fine. @burtrw to have a look as well. 😄

[Imran92]

Maybe we can shorten it like this

.sensei-students__call-to-action {
	display: flex;
	flex-flow: column;
	margin: 20px auto;
	
    div {
		margin: 8px auto;
    }
}

[merkushin]

Thanks, @Imran92! Updated PR.

[Imran92]

Looks good to me and works well 👍 Just have a small point about the SCSS

[Imran92]

Looks great to me 👍