split query resolvers into separate files

src/resolvers/QueryResolvers.ts

@@ -0,0 +1,20 @@
+import { ServerContext } from "../ServerContext";
+import { Resolvers } from "../generated/graphql";
+
+export const QueryResolvers: Resolvers<ServerContext> = {
+  Query: {
+    systems: async (parent, args, contextValue, info) => {
+      return await contextValue.repository.getSystems();
+    },
+    system: async (parent, args, contextValue, info) => {
+      if (!args.id) return null;
+      const system = await contextValue.repository.getSystemById(args.id);
+      if (system === null) return null;
+
+      return {
+        name: system.name,
+        id: system.id,
+      };
+    }
+  },
+}