Merge #693(kitsune): Enable key backup API #1391

Job	Run time
CI (ubuntu-22.04, 6.4, e2ee)	7m 49s
CI (ubuntu-22.04, 6.4)	4m 10s
CI (ubuntu-22.04, 6.4, GCC, e2ee)	13m 3s
CI (ubuntu-22.04, 6.4, GCC)	7m 6s
CI (ubuntu-22.04, 5.15, e2ee)	6m 49s
CI (macos-11, 6.4, e2ee)	8m 23s
CI (macos-11, 6.4)	6m 16s
CI (macos-11, 5.15, e2ee)	8m 52s
CI (windows-2019, 6.4, e2ee)	9m 12s
CI (windows-2019, 6.4)	5m 11s
CI (windows-2019, 5.15, e2ee)	8m 51s
CI (ubuntu-22.04, 5.15, e2ee, update-api, codeql)	15m 20s
CI (ubuntu-22.04, 5.15, GCC, update-api)	9m 14s
	1h 50m 16s

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