feat: add http as smtp provider (#8545)

# Which Problems Are Solved

Send Email messages as a HTTP call to a relay, for own logic on handling
different Email providers

# How the Problems Are Solved

Create endpoints under Email provider to manage SMTP and HTTP in the
notification handlers.

# Additional Changes

Clean up old logic in command and query side to handle the general Email
providers with deactivate, activate and remove.

# Additional Context

Partially closes #8270

---------

Co-authored-by: Livio Spring <livio.a@gmail.com>

internal/notification/channels/email/config.go

@@ -0,0 +1,17 @@
+package email
+
+import (
+	"github.com/zitadel/zitadel/internal/notification/channels/smtp"
+	"github.com/zitadel/zitadel/internal/notification/channels/webhook"
+)
+
+type Config struct {
+	ProviderConfig *Provider
+	SMTPConfig     *smtp.Config
+	WebhookConfig  *webhook.Config
+}
+
+type Provider struct {
+	ID          string `json:"id,omitempty"`
+	Description string `json:"description,omitempty"`
+}