Where are you: swap timezone map & dropdowns

[jpnurmi]

Leaving a 180px vertical gap below the dropdowns makes the timezone map look squeezed (the slightly wrong window height (#697) makes it even worse). Therefore, I'd propose swapping the order to let the popups open over the timezone map.

Before	Design	Proposal

Design: https://people.canonical.com/~platform/desktop/installer/13.%20Where%20Are%20You/#artboard0
Resolves: #1189

[jpnurmi]

@elioqoshi There's an issue in Flutter that dropdowns always open downwards even if there's no space. Would it be a reasonable workaround to change the page layout so that the dropdowns are at the top until Flutter might fix them to open upwards when there's no space below?

[jpnurmi]

Flutter 3.7 introduced a new M3 DropdownMenu that seemed to open upwards when at the bottom of the screen. We could give it a try for this.

[elioqoshi]

@jpnurmi Sorry I missed this before. Let me know if I should review it, the original proposal makes sense and I think the dropdown should be a primary way of selecting your timezone anyway

[jpnurmi]

@elioqoshi The looks have evolved a little since the proposal was originally created but here's how it would look like today. Does it still look ok to you?

[elioqoshi]

This is fully accessible via keyboard, right? Then it looks good to me!

[jpnurmi]

Great, thanks! Yes, these are fully accessible via keyboard 👍

[d-loose]

LGTM 👍