build: use mysqldump to backup/restore databases

Makefile

@@ -482,6 +482,13 @@ dev.dbcopy8.%: ## Copy data from old mysql 5.7 container into a new 8 db
 dev.dbshell.%: ## Run a SQL shell on the given database.
 	docker compose exec mysql80 bash -c "mysql $*"
 
+dev.mysqldumpall:
+	docker compose exec mysql80 mysqldump --all-databases > .dev/devstackall.sql
+
+dev.mysqlrestoredump: dev.up.mysql80
+	sleep 10 # give it time
+	docker compose exec -T mysql80 mysql < .dev/devstackall.sql
+
 # List of Makefile targets to run static asset generation, in the form dev.static.$(service)
 # Services will only have their asset generation added here
 # if the service is present in both $(DEFAULT_SERVICES) and $(ASSET_SERVICES).