[UI] Adjust gitauth layout to remain consistent across screen sizes

[AlinaGoaga]

Closes #3266

[foot]

The dropdown becomes very long now. I'm not sure the best way to reconcile this.

Constraints

• "Authenticate" button should be right next to the dropdown as mentioned in the linked issue here
• Source dropdown to select what we're authenticating should perhaps not be the width of the page (or?)

Resolve by?

• Dropdown becomes "50%" as the above commit / description etc fields?
• Where does the field go? (left / right aligned?)

Do we have a design in figma?

cc @mmoulian

[foot]

Also! Wide screens might be rarer, and this is defo an improvement to my eyes as it stands.

Happy to merge as is and come up with another design for super wide screens later. Maybe max-widthing the entire form is another option.

[mmoulian]

@foot @AlinaGoaga Sure, I can do a design in Figma. I'll be able to start on this next week.
I have a high priority delivery next Monday.

[AlinaGoaga]

Thanks @mmoulian ping me pls when ready (no rush)

[alfaris]

I advice that set a max width for this section to 1024px and min width to 375px

here the design

And let me know if I missed anything