Add split screen to new renderer

[tomas7770]

Description

Ports the splitscreen plugin to the new renderer. For each DrawsTo relation with a target that has a SplitScreen component, the plugin sets the viewport in the relation. Plugins which draw to the target should use this viewport.

Checklist

• [x] Self-review changes.
• [ ] Evaluate impact on the documentation.
• [ ] Ensure test coverage.
• [x] Write new samples.
• [x] 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-1155/ on branch gh-pages at 2024-05-05 10:41 UTC

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 97 lines in your changes are missing coverage. Please review.

Project coverage is 39.45%. Comparing base (c68a5f2) to head (9e55fcd).

Files	Patch %	Lines
engine/src/render/split_screen/plugin.cpp	0.00%	40 Missing :warning:
engine/src/render/ssao/plugin.cpp	0.00%	22 Missing :warning:
engine/src/render/deferred_shading/plugin.cpp	0.00%	17 Missing :warning:
engine/src/render/g_buffer_rasterizer/plugin.cpp	0.00%	12 Missing :warning:
engine/src/render/camera/draws_to.cpp	0.00%	4 Missing :warning:
engine/src/render/split_screen/split_screen.cpp	0.00%	2 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1155 +/- ## ========================================== - Coverage 39.57% 39.45% -0.13% ========================================== Files 346 348 +2 Lines 26130 26211 +81 ========================================== Hits 10342 10342 - Misses 15788 15869 +81 ```

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