module: Add top-level mod_telemetry.h and introduce telemetry module

• Introduced mod_telemetry.h as the top-level header for telemetry support.
• Defined telemetry data event types, descriptors, and update interval formats.
• Established API definitions for telemetry sources and SHMTI handling.

Signed-off-by: Girish Pathak girish.pathak@arm.com