feat: add DistanceNoiseStd and FlipHitProbability to RayPerceptionSensor

[raelbarros]

Proposed change(s)

Adds native noise support to ray-based perception sensors.

Together these parameters let users add controlled realistic imperfection directly from the Inspector, simulating real-world sensor noise, making the system more robust.

New public fields on RayPerceptionSensorComponents:

• DistanceNoiseStd – Adds zero-mean Gaussian noise to HitFraction, the normalised distance returned by each ray.
• FlipHitProbability – Given probability to inverts the boolean HasHit flag of the ray (0 → 1 or 1 → 0).

Core logic implemented inside RayPerceptionSensor.ApplyNoise, called during Write() so that observations fed to the policy already include noise.

Editor updated: a Noise fold-out appears in the Inspector with the two sliders.

Docs & CHANGELOG updated accordingly. Default values 0 keep full backward compatibility.

Useful links (Github issues, JIRA tickets, ML-Agents forum threads etc.)

n/a

Types of change(s)

• Bug fix
• New feature
• Code refactor
• Breaking change
• Documentation update
• Other (please describe)

Checklist

• Added tests that prove my fix is effective or that my feature works
• Updated the changelog (if applicable)
• Updated the documentation (if applicable)
• Updated the migration guide (if applicable)

Other comments