feat: generate webkeys setup step (#10105)

# Which Problems Are Solved

We are preparing to roll-out and stabilize webkeys in the next version
of Zitadel. Before removing legacy signing-key code, we must ensure all
existing instances have their webkeys generated.

# How the Problems Are Solved

Add a setup step which generate 2 webkeys for each existing instance
that didn't have webkeys yet.

# Additional Changes

Return an error from the config type-switch, when the type is unknown.

# Additional Context

- Part 1/2 of https://github.com/zitadel/zitadel/issues/10029
- Should be back-ported to v3

cmd/setup/config.go

@@ -155,6 +155,7 @@ type Steps struct {
 	s56IDPTemplate6SAMLFederatedLogout      *IDPTemplate6SAMLFederatedLogout
 	s57CreateResourceCounts                 *CreateResourceCounts
 	s58ReplaceLoginNames3View               *ReplaceLoginNames3View
+	s59SetupWebkeys                         *SetupWebkeys
 }
 
 func MustNewSteps(v *viper.Viper) *Steps {