sim: fake IMU data in simulator

[Mifrill]

Description

Adds IMU (accelerometer and gyroscope) data generation to the MetaDrive simulator and creates a test to validate the data flow. This addresses issue #33721 by providing fake IMU sensor data that can be used for testing and development.

The fix consists of two commits:

1. sim: fake IMU data in simulator - Added IMU data generation in MetaDrive world that creates realistic accelerometer and gyroscope readings using mathematical functions
2. test: add test for sim IMU data - Created test to validate IMU data is properly generated and flows through the messaging system

Verification

• Verified IMU services (accelerometer and gyroscope) are available in the messaging system
• Confirmed the MetaDrive bridge can create and initialize with IMU data generation
• Test infrastructure is working - messaging setup and service discovery functions correctly
• The test validates that IMU data is generated with proper variance (>1e-3) to ensure non-static readings
• Used the current accelerometer and gyroscope services (not deprecated sensorEvents)

Technical Details

• IMU data is generated using mathematical functions to simulate realistic sensor readings
• Data flows through the standard openpilot messaging system using Cap'n Proto
• Test validates both data presence and statistical properties

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[Mifrill]

📝 TODO: Sync with #33836

[Mifrill]

📝 703f3d0#r175851715