Add basic layout system support

[codecov[bot]]

Codecov Report

Attention: 133 lines in your changes are missing coverage. Please review.

Comparison is base (7481074) 14.35% compared to head (fbe0252) 13.94%.

Files	Patch %	Lines
...t/LayoutFundamentals/internal/LayoutComputer.swift	0.00%	29 Missing :warning:
...I/Layout/LayoutFundamentals/internal/Spacing.swift	0.00%	22 Missing :warning:
...ayoutAdjustments/Alignment/VerticalAlignment.swift	0.00%	16 Missing :warning:
...t/LayoutAdjustments/Alignment/ViewDimensions.swift	0.00%	14 Missing :warning:
...out/LayoutAdjustments/Alignment/AlignmentKey.swift	0.00%	13 Missing :warning:
...outAdjustments/Alignment/HorizontalAlignment.swift	0.00%	12 Missing :warning:
...es/OpenSwiftUI/Views/View/TODO/_VariadicView.swift	0.00%	8 Missing :warning:
...iftUI/Layout/LayoutFundamentals/Stack/HStack.swift	0.00%	7 Missing :warning:
...OpenSwiftUI/Views/Animations/TODO/Animatable.swift	0.00%	4 Missing :warning:
...ayout/LayoutFundamentals/Stack/_HStackLayout.swift	0.00%	3 Missing :warning:
... and 3 more

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #7 +/- ## ========================================== - Coverage 14.35% 13.94% -0.41% ========================================== Files 123 132 +9 Lines 1700 1785 +85 ========================================== + Hits 244 249 +5 - Misses 1456 1536 +80 ```

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