This commit introduces the stm_cpu test script designed to validate the System Trace Macrocell (STM) functionality on the target platform. The script performs a series of steps including:

• Verifying required kernel configurations for STM support
• Mounting configfs and debugfs if not already mounted
• Creating STM policy directories and enabling ETF sink
• Loading STM-related kernel modules (stm_heartbeat, stm_console, stm_ftrace)
• Linking STM source to ftrace and enabling tracing
• Capturing trace output and validating its presence

The script generates a result file (stm_cpu.res) indicating PASS, FAIL, or SKIP based on the outcome of the test.

Additionally, a detailed README.md is added, covering:

• Test overview and objectives
• Usage instructions and prerequisites
• Result format and sample logs

This test ensures that the STM infrastructure is correctly configured and functional for trace capture on supported platforms.