Add support for ui_locales parameter #1728

Job	Run time
Security checks	25s
Syntax and unit tests, PHP 8.3,	1m 2s
Syntax and unit tests, PHP 8.4,	1m 1s
conformance-suite (dev-simplesamlphp-2.5)	12m 17s
Syntax and unit tests, PHP 8.5,	1m 3s
Sanity checks	23s
Quality control	1m 0s
	17m 11s

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