Update PHP_PSALM linter environment

[llaville]

Is your feature request related to a problem? Please describe.
It's not a problem. We should consider as an improvement for the PHP_PSALM linter configuration.

Describe the solution you'd like

• Add php83-opcache extension with apk to the PHP descriptor file :
  • https://github.com/oxsecurity/megalinter/blob/main/megalinter/descriptors/php.megalinter-descriptor.yml
• Add new entries findUnusedCode and findUnusedBaselineEntry in psalm.xml template file :
  • https://github.com/oxsecurity/megalinter/blob/main/TEMPLATES/psalm.xml

Describe alternatives you've considered
Keep configuration in state

Additional context
E.g: Report produced by scanning megalinter/.automation/test/php directory of this repo !

[psalm] command: ['psalm', '--output-format=console', '--config=/action/lib/.automation/psalm.xml', 'php_bad_1.php', 'php_bad_2.php', 'php_good_1.php', 'php_good_2.php']
[psalm] CWD: /tmp/lint
[psalm] result: 2 Warning: "findUnusedBaselineEntry" will default to "true" in Psalm 6. You should explicitly enable or disable this setting.
Warning: "findUnusedCode" will default to "true" in Psalm 6. You should explicitly enable or disable this setting.

Install the opcache extension to make use of JIT on PHP 8.0+ for a 20%+ performance boost!

Target PHP version: 8.3 (inferred from current PHP version).
Scanning files...
Analyzing files...

[llaville]

New branch features/php-psalm-improvement available with updates : 067b070

[llaville]

Spell Linter is a bit rough when new word is not in is dictionary :

[llaville]

cspell issue fixed by new commit a940b87