feat: add `delegate` authenticator #661

Job	Run time
Generate SDKs	1m 9s
Run tests and lints	2m 21s
Run tests (reload)	1m 22s
Run tests (e2e)	58s
Run tests (forwarded-header)	55s
Run tests (bearer-token)	56s
Build CLI docs	1m 33s
Generate changelog	0s
Generate release	0s
Render version schema	0s
Draft newsletter	0s
Release SDKs	0s
Send newsletter	0s
Pending approval Slack notification	0s
	9m 14s

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