Fix zabbix_user module not working with Zabbix 5.4

[href]

With 5.4, 'alias' has been renamed to 'username'. With this change it is
possible to use both parameters. The right one will be sent to the Zabbix
server transparently, depending on the server's version.

Resolves #398.

[codecov]

Codecov Report

Merging #406 (09ae63d) into main (03421c8) will decrease coverage by 2.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #406      +/-   ##
==========================================
- Coverage   78.78%   76.75%   -2.03%     
==========================================
  Files          19       21       +2     
  Lines        2635     2960     +325     
  Branches      665      761      +96     
==========================================
+ Hits         2076     2272     +196     
- Misses        364      452      +88     
- Partials      195      236      +41     

Impacted Files	Coverage Δ
...s/community/zabbix/plugins/modules/zabbix_proxy.py	50.00% <0.00%> (-40.17%)	⬇️
...ns/community/zabbix/plugins/modules/zabbix_user.py	88.94% <0.00%> (-0.29%)	⬇️
...ns/community/zabbix/plugins/modules/zabbix_host.py	83.33% <0.00%> (-0.18%)	⬇️
...community/zabbix/plugins/modules/zabbix_service.py	86.13% <0.00%> (ø)
...unity/zabbix/plugins/modules/zabbix_globalmacro.py	72.03% <0.00%> (ø)
...unity/zabbix/plugins/modules/zabbix_maintenance.py	68.21% <0.00%> (ø)
...ity/zabbix/plugins/modules/zabbix_template_info.py	80.95% <0.00%> (+0.95%)	⬆️
...ommunity/zabbix/plugins/modules/zabbix_template.py	77.99% <0.00%> (+1.89%)	⬆️
...s/community/zabbix/plugins/module_utils/helpers.py	75.00% <0.00%> (+2.58%)	⬆️

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[D3DeFi]

Thank you for this patch. Pipeline for zabbix 5.4 is not enabled in our repo yet as it would fail, but running tests locally:

zabbix_version=5.4 docker-compose up -d
ansible-test integration test_zabbix_user

results in tests passing.