Add UI base

[DiogoMendonc-a]

Added:

• UI Canvas

• UI Element, with offsets, pivots, anchors and all that cool jazz

• Vertical and Horizontal stretching

• Color rect, for drawing colors

• [ ] Self-review changes.

• [ ] Evaluate impact on the documentation.

• [ ] Ensure test coverage.

• [ ] Write new samples.

• [ ] Add entry to the changelog's unreleased section.

[github-actions[bot]]

PR Preview Action v1.4.7 :---: :rocket: Deployed preview to https://GameDevTecnico.github.io/cubos/docs-preview/pr-1173/ on branch gh-pages at 2024-05-09 18:05 UTC

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 182 lines in your changes are missing coverage. Please review.

Project coverage is 40.48%. Comparing base (fb1cfbf) to head (e884a24).

Files	Patch %	Lines
engine/src/ui/canvas/plugin.cpp	0.00%	70 Missing :warning:
engine/src/ui/color_rect/plugin.cpp	0.00%	65 Missing :warning:
engine/src/ui/canvas/element.cpp	0.00%	12 Missing :warning:
core/src/ecs/cubos.cpp	0.00%	11 Missing :warning:
engine/src/ui/canvas/horizontal_stretch.cpp	0.00%	5 Missing :warning:
engine/src/ui/canvas/vertical_stretch.cpp	0.00%	5 Missing :warning:
engine/src/defaults/plugin.cpp	0.00%	4 Missing :warning:
engine/src/ui/canvas/canvas.cpp	0.00%	4 Missing :warning:
engine/src/ui/color_rect/color_rect.cpp	0.00%	4 Missing :warning:
core/include/cubos/core/ecs/cubos.hpp	0.00%	2 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1173 +/- ## ========================================== - Coverage 40.77% 40.48% -0.29% ========================================== Files 342 349 +7 Lines 25744 25925 +181 ========================================== Hits 10496 10496 - Misses 15248 15429 +181 ```

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