IBX-4123: [Backport] Added `/languages` and `/languages/{code}` endpo… #100

Job	Run time
Run code style check	36s
Unit tests (7.3)	31s
Unit tests (7.4)	41s
Unit tests (8.0)	30s
Unit tests (8.2)	1m 10s
REST integration tests / integration-tests-rest	9m 7s
	12m 35s

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