Tests

Translate channel names and support an array of channels in file upload. #1382

Job	Run time
test (ruby=2.7)	30s
test (ruby=2.7, concurrency=async-websocket)	33s
test (ruby=3.0)	18s
test (ruby=3.1)	18s
test (ruby=3.2)	20s
test (ruby=3.3)	20s
test (ruby=ruby-head)	20s
test (ruby=jruby-head)	1m 54s
coveralls	2s
	4m 35s

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