common: add admin socket control and CMake flag for cputrace

common: add admin socket control and CMake flag for cputrace

- Introduced a separate CMake flag to enable cputrace:
    cmake -DWITH_CPUTRACE=1 ...

- Added admin socket interface for runtime control:
    - `ceph tell osd.X cputrace start`   → Start profiling
    - `ceph tell osd.X cputrace stop`    → Stop profiling
    - `ceph tell osd.X cputrace dump`    → Dump collected metrics
    - `ceph tell osd.X cputrace reset`   → Reset profiling state

This enables developers to dynamically control profiling during runtime
without rebuilding or restarting the OSD, and ensures `cputrace` remains
disabled in production unless explicitly enabled at build time.

Signed-off-by: Jaya Prakash <jayaprakash@ibm.com>