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/server.go

@@ -6,6 +6,7 @@ import (
 	"time"
 
 	"npm/internal/logger"
+	"npm/internal/serverevents"
 )
 
 const httpPort = 3000
@@ -20,6 +21,8 @@ func StartServer() {
 		ReadHeaderTimeout: 3 * time.Second,
 	}
 
+	defer serverevents.Shutdown()
+
 	err := server.ListenAndServe()
 	if err != nil {
 		logger.Error("HttpListenError", err)