Massive rework of platform layer user/organization

The goal of this rework is to make it so I can pass around platform.User
instead of a pair of models.Organization and models.User. This is useful
for reason I kind of forget now, but it started with working on
notifications and ballooned massively from there into refactoring a
number of things that were bugging me.

This also includes a tiny amount of work on server-side events (SSE).

 * background stuff lives inside the platform now, which I need for
   having it push updates through SSE
 * userfile now lives in the platform, under file, so other platform
   functions can safely use it
 * oauth is broken into pieces and inside platform because other stuff
   was calling it already, but badly.
 * notifications go into the platform as well

background/email.go

@@ -1,44 +0,0 @@
-package background
-
-import (
-	"context"
-
-	"github.com/Gleipnir-Technology/nidus-sync/platform/email"
-	"github.com/rs/zerolog/log"
-)
-
-var channelJobEmail chan email.Job
-
-func ReportSubscriptionConfirmationEmail(destination, report_id string) {
-	enqueueJobEmail(email.NewJobReportNotificationConfirmation(
-		destination,
-		report_id,
-	))
-}
-
-func enqueueJobEmail(job email.Job) {
-	select {
-	case channelJobEmail <- job:
-		return
-	default:
-		log.Warn().Msg("email job channel is full, dropping job")
-	}
-}
-
-func startWorkerEmail(ctx context.Context, channel chan email.Job) {
-	go func() {
-		log.Debug().Msg("Email worker started")
-		for {
-			select {
-			case <-ctx.Done():
-				log.Info().Msg("Email worker shutting down.")
-				return
-			case job := <-channel:
-				err := email.Handle(ctx, job)
-				if err != nil {
-					log.Error().Err(err).Msg("Failed to handle email message")
-				}
-			}
-		}
-	}()
-}