Add test verifying that whitespace is not allowed in xs:language values #1210

Job	Run time
Quality control	45s
Security checks	14s
PHP-Linter (8.3) / linter	14s
PHP-Linter (8.4) / linter	17s
PHP-Linter (8.2) / linter	22s
Linter / json-linter	26s
Linter / yaml-linter	7s
Linter / ecmascript-linter	-1s
Linter / style-linter	-1s
Unit tests, PHP 8.4, windows-latest	50s
Unit tests, PHP 8.2, windows-latest	41s
Unit tests, PHP 8.2, ubuntu-latest	22s
Unit tests, PHP 8.4, ubuntu-latest	19s
Unit tests, PHP 8.3, windows-latest	57s
Unit tests, PHP 8.3, ubuntu-latest	23s
Code coverage	6s
Cleanup artifacts	5s
	6m 6s

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