feat: add `delegate` authenticator #663

Job	Run time
Generate SDKs	1m 3s
Run tests and lints	2m 22s
Run tests (reload)	1m 17s
Run tests (e2e)	55s
Run tests (forwarded-header)	53s
Run tests (bearer-token)	54s
Build CLI docs	1m 24s
Generate changelog	0s
Generate release	0s
Release SDKs	0s
Render version schema	0s
Draft newsletter	0s
Pending approval Slack notification	0s
Send newsletter	0s
	8m 48s

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