Add allowUnauthenticatedAll() convenience wrapper #630

Job	Run time
cs-stan / Coding Standard & Static Analysis	34s
testsuite / testsuite-linux (8.4, highest, false)	1m 16s
testsuite / testsuite-linux (8.2, highest, false)	34s
testsuite / testsuite-linux (8.1, highest, false)	44s
testsuite / testsuite-linux (8.1, lowest, false)	37s
testsuite / testsuite-linux (8.3, highest, false)	34s
	4m 19s

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