Add tests for supervisor request handlers #485

Job	Run time
Build Go Tests	1m 26s
build / Build	7m 9s
Docker Tests (basics)	57s
E2E Tests (startup)	12m 43s
Docker Tests (bootstraptoken)	41s
Docker Tests In GO	0s
E2E Tests (s3)	9m 18s
Docker Tests (cacerts)	42s
E2E Tests (btrfs)	4m 23s
Docker Tests (compat)	2m 29s
E2E Tests (externalip)	6m 54s
Docker Tests (lazypull)	58s
E2E Tests (privateregistry)	7m 7s
Docker Tests (upgrade)	2m 17s
E2E Tests (embeddedmirror)	6m 20s
E2E Tests (wasm)	5m 1s
	1h 8m 25s

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