feat: add http as sms provider (#8540)

# Which Problems Are Solved

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

# How the Problems Are Solved

Add HTTP as SMS provider type and handling of webhook messages in the
notification handlers.

# Additional Changes

Clean up old Twilio events, which were supposed to handle the general
SMS providers with deactivate, activate and remove.

# Additional Context

Partially closes #8270

---------

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

internal/notification/channels/sms/config.go

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