E2E: Improve tests, lint, and add more drivers (#855)

This PR introduces lint to cypress code, adds drivers to try and
abstract the usage of cypress as much as possible.
Nothing very interesting, mainly to try out the driver pattern for the
e2e tests.

cypress/e2e/modal-driver.ts

@@ -0,0 +1,42 @@
+import { v1 as uuid } from "uuid";
+import CypressWrapperDriver from "./cypress-wrapper-driver";
+
+export default class ModalDriver {
+  private helper = new CypressWrapperDriver();
+
+  public when = {
+    fillLayers: (opts: {type: string, layer?: string, id?: string}) => {
+      let type = opts.type;
+      let layer = opts.layer;
+      let id;
+      if (opts.id) {
+        id = opts.id;
+      } else {
+        id = `${type}:${uuid()}`;
+      }
+        
+      this.helper.get.element("add-layer.layer-type.select").select(type);
+      this.helper.get.element("add-layer.layer-id.input").type(id);
+      if (layer) {
+        this.helper.when.within(() => {
+          this.helper.get.elementByClassOrType("input").type(layer!);
+        }, "add-layer.layer-source-block")
+      }
+      this.helper.when.click("add-layer");
+        
+      return id;
+    },
+
+    open: () => {
+      this.helper.when.click("layer-list:add-layer");
+      
+      this.helper.get.element("modal:add-layer").should("exist");
+      this.helper.get.element("modal:add-layer").should("be.visible");
+    },
+
+    close: (key: string) => {
+      this.helper.when.waitUntil(() => this.helper.get.element(key));
+      this.helper.when.click(key + ".close-modal");
+    },
+  }
+}