Add ext-sodium and use local phpcs #241

Job	Run time
PHP-Linter (8.5) / linter	18s
PHP-Linter (8.3) / linter	12s
PHP-Linter (8.4) / linter	11s
Linter / yaml-linter	5s
Linter / json-linter	27s
Linter / ecmascript-linter	-1s
Linter / style-linter	-1s
Unit tests, PHP 8.3, ubuntu-latest	32s
Unit tests, PHP 8.5, windows-latest	1m 3s
Unit tests, PHP 8.4, ubuntu-latest	27s
Unit tests, PHP 8.4, windows-latest	1m 7s
Unit tests, PHP 8.3, windows-latest	1m 8s
Unit tests, PHP 8.5, ubuntu-latest	31s
Code coverage	8s
Security checks	32s
Quality control	35s
Cleanup artifacts	3s
	7m 17s

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