Allow not overwriting entity visibility with debug renderer

[Dentosal]

Objective

Currently PhysicsDebugPlugin always overwrites Visibility component of the entity with Collider. This is sometimes undesirable, as I want to have entities whose visibilty is part of the game logic.

Solution

This PR allows the debug renderer to instead not overwrite the visibilty when configured to do so. The PR also changes the default value to not overwrite, as it always forced colliders to be visibile before.

Alternatives

An Option<Visibility> could be used instead of an enum, but I hope this version is more readable. We could also just not change visibility if hide_meshes is set to false, but this would unexpectedly affect visibility if this is toggled.

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Migration Guide

The hide_meshes: bool field of PhysicsGizmos (global) and DebugRender (entity) has been replaced with mesh_visibility: MeshVisibility. The old value true should be MeshVisibility::AlwaysHide, and false should be MeshVisibility::AlwaysShow.

The debug renderer no longer forces entities with Collider to be visible by default. To restore old behavior, set the mesh_visibility field to one of the variants described above.

[janhohenheim]

Marking as Waiting-on-Author due to merge conflicts

[Dentosal]

Marking as Waiting-on-Author due to merge conflicts

Reworked the conflicting segments, should be good to go again