Persistent Vehicle Loadouts (#863)

* persisting vehicle loadouts in between sessions, saving to db and loading from db

* reusing refactored code for clob; initial loadout without empty entries; reverting method of stopping session child actors

server/src/main/resources/db/migration/V004__VehicleLoadout.sql

@@ -0,0 +1,8 @@
+CREATE TABLE IF NOT EXISTS "vehicleloadout" (
+  "id" SERIAL PRIMARY KEY NOT NULL,
+  "avatar_id" INT NOT NULL REFERENCES avatar (id),
+  "loadout_number" INT NOT NULL,
+  "name" VARCHAR(36) NOT NULL,
+  "vehicle" SMALLINT NOT NULL,
+  "items" TEXT NOT NULL
+);