Add Wunderlist migration (#46)

Complete migration flow

Add migration in progress animation

Add handling wunderlist migration flow

Basic migration init structure

Add migrator structure

Co-authored-by: kolaente <k@knt.li>
Reviewed-on: https://kolaente.dev/vikunja/frontend/pulls/46

src/services/migrator/abstractMigrationService.js

@@ -0,0 +1,20 @@
+import AbstractService from '../abstractService'
+
+// This service builds on top of the abstract service and basically just hides away method names.
+// It enables migration services to be created with minimal overhead and even better method names.
+export default class AbstractMigrationService extends AbstractService {
+	constructor(serviceUrlKey) {
+		super({
+			update: '/migration/'+serviceUrlKey+'/migrate',
+			get: '/migration/'+serviceUrlKey+'/auth',
+		})
+	}
+
+	getAuthUrl() {
+		return this.get({})
+	}
+
+	migrate(data) {
+		return this.update(data)
+	}
+}

src/services/migrator/wunderlist.js

@@ -0,0 +1,7 @@
+import AbstractMigrationService from './abstractMigrationService'
+
+export default class WunderlistMigrationService extends AbstractMigrationService {
+	constructor() {
+		super('wunderlist')
+	}
+}