sched/mmcid: Use proper data structures

sched/mmcid: Use proper data structures

Having a lot of CID functionality specific members in struct task_struct
and struct mm_struct is not really making the code easier to read.

Encapsulate the CID specific parts in data structures and keep them
separate from the stuff they are embedded in.

No functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://patch.msgid.link/20251119172549.131573768@linutronix.de