Certificates Renewal + SSE

- Certificate renewal is just a re-request as it's forced already
- Rejig the routes for readability
- Added Server Side Events so that the UI would invalidate the
cache when changes happen on the backend, such as certs being
provided or failing
- Added a SSE Token, which has the same shelf life as normal token
but can't be used interchangeably. The reason for this is, the
SSE endpoint needs a token for auth as a Query param, so it would
be stored in log files. If someone where to get a hold of that,
it's pretty useless as it can't be used to change anything, only
to listen for events until it expires
- Added test endpoint for SSE testing only availabe in debug mode

backend/internal/api/handler/sse_notification.go

@@ -0,0 +1,28 @@
+package handler
+
+import (
+	"encoding/json"
+	"net/http"
+
+	c "npm/internal/api/context"
+	h "npm/internal/api/http"
+	"npm/internal/serverevents"
+)
+
+// TestSSENotification specifically fires of a SSE message for testing purposes
+// Route: POST /sse-notification
+func TestSSENotification() func(http.ResponseWriter, *http.Request) {
+	return func(w http.ResponseWriter, r *http.Request) {
+		bodyBytes, _ := r.Context().Value(c.BodyCtxKey).([]byte)
+
+		var msg serverevents.Message
+		err := json.Unmarshal(bodyBytes, &msg)
+		if err != nil {
+			h.ResultErrorJSON(w, r, http.StatusBadRequest, h.ErrInvalidPayload.Error(), nil)
+			return
+		}
+
+		serverevents.Send(msg, "")
+		h.ResultResponseJSON(w, r, http.StatusOK, true)
+	}
+}