Add new workflow to test dart-dio samples (#21838) #18

Job	Run time
test (ubuntu-latest, 3.9.0, samples/openapi3/client/petstore/dart-dio/oneof_polymorphism_and_inhe...	50s
test (ubuntu-latest, 3.9.0, samples/openapi3/client/petstore/dart-dio/binary_response/)	48s
test (windows-latest, 3.9.0, samples/openapi3/client/petstore/dart-dio/oneof_polymorphism_and_inh...	1m 26s
test (windows-latest, 3.9.0, samples/openapi3/client/petstore/dart-dio/oneof/)	1m 15s
test (windows-latest, 3.9.0, samples/openapi3/client/petstore/dart-dio/binary_response/)	1m 18s
test (ubuntu-latest, 3.9.0, samples/openapi3/client/petstore/dart-dio/oneof/)	45s
	6m 22s

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