Describe the bug

Some unit forms in Edit Lecture are very inconsistent.
Sometimes the form is aligned to the left, sometimes it is centered
and in another case the submit and cancel buttons are swapped and on the other side as usual.
I would like to correct these inconsistencies here.
For more information take a look at the screenshots.

To Reproduce

1. Go to a Course with lectures
2. Click on Lectures
3. Click on Manage
4. Click on Edit
5. Scroll down till you see Add a new Lecture Unit
6. Take a look at Exercise, Video and Online

Expected behavior

All of them should be aligned like the File Unit.
The buttons of the form should also be arranged in the correct order at the bottom left.

Screenshots

I think this is how it should look like (File Unit):

Only the last part is centered (Video Unit):

Everything is centered again (Online Unit):

This one is centered and has its buttons swapped and on the other side with no spacing to the form (Exercise Unit):

Which version of Artemis are you seeing the problem on?

7.9.0

What browsers are you seeing the problem on?

Chrome, Microsoft Edge, Firefox, Other (specify in "Additional context")

Additional context

No response

Relevant log output