fix(detector): fix player detection by guards and cameras

[olivierperez]

I've implemented a new Detector mechanism which is used by cameras and guards to check if they can see the player.

Description

This Detector remembers if player is still in the detection area until he gets out. On each _process call, if player is still in the area, it will trigger a raycast to check if it sees the player and emit a signal when it does.

Motivation and Context

There was a bug when player entered the detection area while partially hidden behind a wall. At this point we didn't detect him and that's what expected, but this issue was if the player, while staying in the detection area, goes fully in front of camera/guard and wasn't detected.

How has this been tested?

I've altered levels to make this cases simpler to test, and I've reset them.

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.

[AnthoMarquet]

@olivierperez J'aurai plutot nommé detector_area la variable pour avoir quelque chose de plus uniforme. On a souvent suffixé par le type de node. Bref un mini détail :)

Test concluant après avoir adapté un niveau pour faire le test.

[olivierperez]

@AnthoMarquet Corrigé b72f196 (#19)