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

platform/communication.go

@@ -0,0 +1,24 @@
+package platform
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/Gleipnir-Technology/nidus-sync/db/models"
+	"github.com/Gleipnir-Technology/nidus-sync/platform/publicreport"
+)
+
+func NotificationCount(ctx context.Context, org *models.Organization, user *models.User) (result uint, err error) {
+	count_nreports, err := publicreport.NuisanceReportForOrganizationCount(ctx, org.ID)
+	if err != nil {
+		return 0, fmt.Errorf("nuisance report query: %w", err)
+	}
+	result += count_nreports
+
+	count_wreports, err := publicreport.WaterReportForOrganizationCount(ctx, org.ID)
+	if err != nil {
+		return 0, fmt.Errorf("water report query: %w", err)
+	}
+	result += count_wreports
+	return result, nil
+}