vyos.utils: T6244: add whitespace after time unit in uptime (backport #3336)

[mergify]

Change Summary

We only supported calculating seconds to weeks but not seconds to years. This has been added.

In addition when handling optional separators rather build up a list and join

This PR thus changes the result of "show system uptime" 2w4d22h54m9s to a more human readable string 2w 4d 22h 54m 9s.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, renaming)
• Refactoring (no functional changes)
• Migration from an old Vyatta component to vyos-1x, please link to related PR inside obsoleted component
• Other (please describe):

Related Task(s)

• https://vyos.dev/T6244

Related PR(s)

Component(s) name

vyos.utils

Proposed changes

How to test

#!/usr/bin/env python3
from vyos.utils.convert import seconds_to_human

minute = 60
hour = minute * 60
day = hour * 24
week = day * 7
year = day * 365.25

for separator in ['', ' ', '-', '/']:
  print(f'----- Using separator "{separator}" -----')
  print(seconds_to_human(10, separator))
  print(seconds_to_human(5* minute, separator))
  print(seconds_to_human(3* hour, separator))
  print(seconds_to_human(4* day, separator))
  print(seconds_to_human(7 * week, separator))
  print(seconds_to_human(10 * year, separator))
  print(seconds_to_human(5*year + 4*week + 3*day + 2*hour + minute + 5, separator))
  print()

yields:

cpo@LR1.wue3:~$ ./foo.py
----- Using separator "" -----
10s
5m
3h
4d
7w
10y
5y4w3d2h1m5s

----- Using separator " " -----
10s
5m
3h
4d
7w
10y
5y 4w 3d 2h 1m 5s

----- Using separator "-" -----
10s
5m
3h
4d
7w
10y
5y-4w-3d-2h-1m-5s

----- Using separator "/" -----
10s
5m
3h
4d
7w
10y
5y/4w/3d/2h/1m/5s

cpo@LR1.wue3:~$ show system uptime
Uptime: 4d 19h 8m 51s

Load averages:
1  minute:   0.0%
5  minutes:  0.0%
15 minutes:  0.0%

Checklist:

• I have read the CONTRIBUTING document
• I have linked this PR to one or more Phabricator Task(s)
• I have run the components SMOKETESTS if applicable
• My commit headlines contain a valid Task id
• My change requires a change to the documentation
• I have updated the documentation accordingly

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This is an automatic backport of pull request #3336 done by [Mergify](https://mergify.com).