Overhaul publicreport storage layer, create unified tables

This is a huge change. I was getting really sick of the split between
nuisance/water tables when more than half of the data they store is
common. I finally bit off the big work of switching it all.

This creates a single unified table, publicreport.report and copies the
existing report data into it. It also ports existing data from the
original tables into the new table.

Along with all of this I also overhauled the system for handling
asynchronous work to use a LISTEN/NOTIFY connection from the database
and a single cache table to avoid ever losing work.

db/dberrors/publicreport.nuisance_image_old.bob.go

@@ -0,0 +1,17 @@
+// Code generated by BobGen psql v0.42.5. DO NOT EDIT.
+// This file is meant to be re-generated in place and/or deleted at any time.
+
+package dberrors
+
+var PublicreportNuisanceImageOldErrors = &publicreportNuisanceImageOldErrors{
+	ErrUniqueNuisanceImagePkey: &UniqueConstraintError{
+		schema:  "publicreport",
+		table:   "nuisance_image_old",
+		columns: []string{"image_id", "nuisance_id"},
+		s:       "nuisance_image_pkey",
+	},
+}
+
+type publicreportNuisanceImageOldErrors struct {
+	ErrUniqueNuisanceImagePkey *UniqueConstraintError
+}