Added sorting, started on paging

src/models/sort.ts

@@ -0,0 +1,19 @@
+import { SORT } from '../enums/sort';
+
+export class Sort {
+  field: string;
+  dir: SORT;
+
+  constructor(data: Partial<Sort>) {
+    this.field = data?.field ?? '';
+    this.dir = data?.dir ?? SORT.NONE;
+  }
+
+  isValid(): boolean {
+    return this.field !== '' && this.dir !== SORT.NONE;
+  }
+
+  toString(): string {
+    return `${this.field}:${this.dir}`;
+  }
+}