Overly wide origin combobox causes layout issues

[mcclurgm]

Prerequisites

• I have searched open and closed issues for duplicates.

Describe the bug

If the ComboBox for origin selection is overly long, it can cause other widgets to be laid out incorrectly. It makes its column take up too much space, so other things can't take the width they need. Here's an example photo:

The "Abbrechen" button is supposed to be inside the column boundaries, which you can see overlap it.
The AppCenter label is wrong (already fixed in git, I hear), but it exposes a potential issue here. I enabled layout bounds to show the dimensions of the widgets. This shows that the progress bar is being pushed to the right by the labels, which are overly long because they match the size of the ComboBox.

Possible Solution

I think I've come up with a solution, but since this requires newer libraries than I have on Hera, I can't test it. Here's what I think we should do:
In AppInfoView.vala line 319, change:

-            header_grid.attach (origin_combo_revealer, 1, 2);
+            header_grid.attach (origin_combo_revealer, 1, 2, 2);

This makes it take up multiple columns. Since there's nothing else in its row, this shouldn't be an issue.

I'd like to submit a PR myself, but I don't feel like I can without knowing whether the code works. Hopefully this is enough info to make one easy for someone else.

Platform Information

• I'm using the latest version from git that I've manually compiled
• I'm using the latest released stable version