feat: Reorganize landscape page

[ashuntu]

Restructures the Landscape page to use the 2 column layout. This comes with quite the large side effect of combining the SaaS and self-hosted configurations into a single set of fields, so there are quite a lot of changes here to support that.

This is based on and relies on #997 being merged first.

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UDENG-5288

[codecov]

Codecov Report

Attention: Patch coverage is 88.60759% with 9 lines in your changes missing coverage. Please review.

Project coverage is 89.20%. Comparing base (d5ce322) to head (a20d697).
Report is 32 commits behind head on main.

Files with missing lines	Patch %	Lines
.../ubuntupro/lib/pages/landscape/landscape_page.dart	83.63%	9 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1008      +/-   ##
==========================================
- Coverage   89.38%   89.20%   -0.19%     
==========================================
  Files         113      113              
  Lines        7618     7528      -90     
==========================================
- Hits         6809     6715      -94     
- Misses        632      637       +5     
+ Partials      177      176       -1     

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[ashuntu]

This probably has a ways to go before it is ready, but I opened for review so we can get started on back and forth :)

[CarlosNihelton]

Let's focus on the models first.
The current design mockups are essentially removing the "support" we had implemented in code for the Landscape SaaS, instead of merging it with the self-hosted option. You can rename it to manual, as you did, but it cannot be made to work with Landscape SaaS at all at this moment.
If my comments are not clear enough let's pair together on this tomorrow.

[CarlosNihelton]

Impressive wok on the UI changes! I just have one minor UX concern. We're almost there.

[CarlosNihelton]

Well done! 🎉