NS CERT ADD <self> <certfp> should not require privileges

[slingamn]

ergo/irc/nickserv.go

Lines 368 to 374 in 5671ee2

	CERT examines or modifies the SHA-256 TLS certificate fingerprints that can
	be used to log into an account. Specifically, $bCERT LIST$b lists the
	authorized fingerprints, $bCERT ADD <fingerprint>$b adds a new fingerprint, and
	$bCERT DEL <fingerprint>$b removes a fingerprint. If you're an IRC operator
	with the correct permissions, you can act on another user's account, for
	example with $bCERT ADD <account> <fingerprint>$b. See the operator manual
	for instructions on how to compute the fingerprint.`,

The two-argument case fails without privileges even when the user is trying to act on their own account:

ergo/irc/nickserv.go

Lines 1414 to 1418 in 5671ee2

	hasPrivs := client.HasRoleCapabs("accreg")
	if target != "" && !hasPrivs {
	service.Notice(rb, client.t("Insufficient privileges"))
	return
	} else if target == "" {

We should detect that the user is acting on themself and make this succeed.

[slingamn]

Resolved by #2128