feat: Integrate setup behaviour

This adds options for enabling setup to the config folder.
All default configs with permanent storage (file/sparql)
are configured to require setup at server start.
Memory-based configs merely have it as an option.

test/unit/util/handlers/StaticHandler.test.ts

@@ -0,0 +1,18 @@
+import { StaticHandler } from '../../../../src/util/handlers/StaticHandler';
+
+describe('A StaticHandler', (): void => {
+  it('can handle everything.', async(): Promise<void> => {
+    const handler = new StaticHandler();
+    await expect(handler.canHandle(null)).resolves.toBeUndefined();
+  });
+
+  it('returns the stored value.', async(): Promise<void> => {
+    const handler = new StaticHandler('apple');
+    await expect(handler.handle()).resolves.toEqual('apple');
+  });
+
+  it('returns undefined if there is no stored value.', async(): Promise<void> => {
+    const handler = new StaticHandler();
+    await expect(handler.handle()).resolves.toBeUndefined();
+  });
+});