Add Cubos::reset method

[RiscadoA]

Description

Adds the reset method to Cubos, which resets the application to its initial state. TL;DR, instead of:

Cubos cubos1;
cubos1.blabla
Cubos cubos2;
cubos2.blabla

you can do

Cubos cubos;
cubos.blablabla
cubos.reset();
cubos.blablabla

This will be useful to allow resetting the game in the editor.

Checklist

• [x] Self-review changes.
• [x] Evaluate impact on the documentation.
• [x] 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-1226/ on branch gh-pages at 2024-06-04 18:03 UTC

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 97.22222% with 2 lines in your changes missing coverage. Please review.

Project coverage is 40.52%. Comparing base (bf733fa) to head (dd7caa5). Report is 2 commits behind head on main.

:exclamation: Current head dd7caa5 differs from pull request most recent head 305470f

Please upload reports for the commit 305470f to get more accurate results.

Files	Patch %	Lines
core/src/ecs/system/registry.cpp	77.77%	2 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1226 +/- ## ========================================== + Coverage 40.32% 40.52% +0.20% ========================================== Files 351 351 Lines 26061 26133 +72 ========================================== + Hits 10508 10590 +82 + Misses 15553 15543 -10 ```

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