Let plugins migrate the data core stores for them

Plugins had no way to update the config fields and permissions core stores
for them, so renaming inventory_sync needed migrations in core packages.

A plugin can now declare a migrationEntrypoint. It's loaded on the
controller and hosts before configs and roles are read, for every plugin in
the plugin list, and attaches handlers to sync hooks for the controller,
host and instance configs and roles. lib gets helpers to rename config
fields and permissions, and each config gets a hidden <plugin>.version field
set after load so migrations can tell which version saved the data.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

test/controller/Controller.js

@@ -11,7 +11,7 @@ import { fileURLToPath } from "node:url";
 import {
 	ControllerConfig, Address, RequestError,
 	InstanceConfig, SystemInfo, Role, ModPack, AccountUpdateEvent,
-	addPluginConfigFields,
+	addPluginConfigFields, renamePermissionPrefix,
 } from "@clusterio/lib";
 
 import "../setup_logging.js";
@@ -714,6 +714,17 @@ describe("controller/src/Controller", function() {
 					{ permissions: ["core.instance.save.subscribe"] },
 				]);
 			});
+			it("runs plugin role migrations", function() {
+				Role.pluginMigrations.attach("test", role => (
+					renamePermissionPrefix(role, "old_name.", "new_name.")
+				));
+				try {
+					const result = Controller.migrateRoles([{ permissions: ["foo", "old_name.view"] }]);
+					assert.deepEqual(result, [{ permissions: ["foo", "new_name.view"] }]);
+				} finally {
+					Role.pluginMigrations.clear();
+				}
+			});
 			it("does nothing for upto date data", function() {
 				const role = new Role(
 					0, "n", "d", new Set("p1", "p2"), 0, false