delaytop: add psi info to show system delay

Support showing whole delay of system by reading PSI, just like the first
few lines of information output by the top command.  the output of
delaytop includes both system-wide delay and delay of individual tasks,
providing a more comprehensive reflection of system latency status.

Use case
========
bash# ./delaytop
System Pressure Information: (avg10/avg60/avg300/total)
CPU:    full:    0.0%/   0.0%/   0.0%/0           some:    0.1%/   0.0%/   0.0%/14216596
Memory: full:    0.0%/   0.0%/   0.0%/34010659    some:    0.0%/   0.0%/   0.0%/35406492
IO:     full:    0.1%/   0.0%/   0.0%/51029453    some:    0.1%/   0.0%/   0.0%/55330465
IRQ:    full:    0.0%/   0.0%/   0.0%/0

Top 20 processes (sorted by CPU delay):

  PID   TGID  COMMAND            CPU(ms)  IO(ms)        SWAP(ms) RCL(ms) THR(ms)  CMP(ms)  WP(ms)  IRQ(ms)
---------------------------------------------------------------------------------------------
   32     32  kworker/2:0H-sy   23.65     0.00     0.00     0.00    0.00     0.00     0.00     0.00
  497    497  kworker/R-scsi_    1.20     0.00     0.00     0.00    0.00     0.00     0.00     0.00
  495    495  kworker/R-scsi_    1.13     0.00     0.00     0.00    0.00     0.00     0.00     0.00
  494    494  scsi_eh_0          1.12     0.00     0.00     0.00    0.00     0.00     0.00     0.00
  485    485  kworker/R-ata_s    0.90     0.00     0.00     0.00    0.00     0.00     0.00     0.00
  574    574  kworker/R-kdmfl    0.36     0.00     0.00     0.00    0.00     0.00     0.00     0.00
   34     34  idle_inject/3      0.33     0.00     0.00     0.00    0.00     0.00     0.00     0.00
 1123   1123  nde-netfilter      0.28     0.00     0.00     0.00    0.00     0.00     0.00     0.00
   60     60  ksoftirqd/7        0.25     0.00     0.00     0.00    0.00     0.00     0.00     0.00
  114    114  kworker/0:2-cgr    0.25     0.00     0.00     0.00    0.00     0.00     0.00     0.00
  496    496  scsi_eh_1          0.24     0.00     0.00     0.00    0.00     0.00     0.00     0.00
   51     51  cpuhp/6            0.24     0.00     0.00     0.00    0.00     0.00     0.00     0.00
 1667   1667  atd                0.24     0.00     0.00     0.00    0.00     0.00     0.00     0.00
   45     45  cpuhp/5            0.23     0.00     0.00     0.00    0.00     0.00     0.00     0.00
 1102   1102  nde-backupservi    0.22     0.00     0.00     0.00    0.00     0.00     0.00     0.00
 1098   1098  systemsettings     0.21     0.00     0.00     0.00    0.00     0.00     0.00     0.00
 1100   1100  audit-monitor      0.20     0.00     0.00     0.00    0.00     0.00     0.00     0.00
   53     53  migration/6        0.20     0.00     0.00     0.00    0.00     0.00     0.00     0.00
 1482   1482  sshd               0.19     0.00     0.00     0.00    0.00     0.00     0.00     0.00
   39     39  cpuhp/4            0.19     0.00     0.00     0.00    0.00     0.00     0.00     0.00

Link: https://lkml.kernel.org/r/20250710135451340_5pOgpIFi0M5AE7H44W1D@zte.com.cn


Co-developed-by: Fan Yu <fan.yu9@zte.com.cn>
Signed-off-by: Fan Yu <fan.yu9@zte.com.cn>
Signed-off-by: Wang Yaxin <wang.yaxin@zte.com.cn>
Signed-off-by: Jiang Kun <jiang.kun2@zte.com.cn>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Peilin He <he.peilin@zte.com.cn>
Cc: Qiang Tu <tu.qiang35@zte.com.cn>
Cc: wangyong <wang.yong12@zte.com.cn>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Yang Yang <yang.yang29@zte.com.cn>
Cc: Yunkai Zhang <zhang.yunkai@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>