ps: improve the parameter output of the ps command

[Franklin-Qi]

Improve the parameter output of the ps command so thatcargo run -q ps -A -e does not report errors.

$ ps -A -e |head -n5 && cargo run -q ps -A -e |head -n5
    PID TTY          TIME CMD
      1 ?        00:00:57 systemd
      2 ?        00:00:00 kthreadd
      3 ?        00:00:00 pool_workqueue_release
      4 ?        00:00:00 kworker/R-rcu_gp
 PID     TTY    TIME      CMD 
 1       ?      00:00:57  systemd 
 2       ?      00:00:00  kthreadd 
 3       ?      00:00:00  pool_workqueue_release 
 4       ?      00:00:00  kworker/R-rcu_gp 

Fix #669

[codecov]

Codecov Report

❌ Patch coverage is 64.28571% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 19.22%. Comparing base (ee98c0a) to head (6c15360).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
src/uu/ps/src/ps.rs	0.00%	4 Missing ⚠️
src/uu/ps/src/process_selection.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #664      +/-   ##
==========================================
+ Coverage   19.19%   19.22%   +0.03%     
==========================================
  Files          68       68              
  Lines       10135    10143       +8     
  Branches      545      546       +1     
==========================================
+ Hits         1945     1950       +5     
- Misses       8190     8193       +3     

Flag	Coverage Δ
macos_latest	6.74% <0.00%> (-0.01%)	⬇️
ubuntu_latest	19.58% <64.28%> (+0.03%)	⬆️
windows_latest	0.02% <0.00%> (-0.01%)	⬇️

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