Support configurable TF frame prefixes

[Daniiiil1]

Overview

Author: Daniil Mordanov

Issue

Issue link: #789

Issue description: Published image, optical, IMU, and calibration TF frames were derived from different prefixes, so a custom multi-robot prefix could not be applied consistently.

Related PRs: None

Changes

ROS distro: Kilted

• add a tf_prefix launch argument, defaulting to the driver node name
• use driver.i_tf_base_frame as the shared frame prefix when calibration TF publishing is enabled
• apply the prefix consistently to image frame IDs, optical frames, IMU messages, and calibration transforms
• keep the robot-state-publisher node name separate from slash-delimited TF prefixes
• preserve the existing node-name behavior when calibration TF publishing is disabled
• add hardware-independent unit coverage for custom and fallback frame prefixes

Addresses #789.

Testing

Hardware used: None
DepthAI library version: N/A

• clang-format --dry-run --Werror on changed C++ files
• black --check on changed launch files
• Python bytecode compilation for changed launch files
• XML validation for depthai_ros_driver/package.xml
• git diff --check

The new gtest is included for the ROS Kilted CI environment.