ESLint parity with the Browsertrix repo (#288)

This copies the rules from the Browsertrix repo, and uses
[`suppress-eslint-errors`](https://www.npmjs.com/package/suppress-eslint-errors)
to suppose the violations. I'll take a pass at cleaning this up at some
point in the future, and let's do our best to address these in the
future as we come across them :)

This'll help ensure new code being added to this repo is held to the
same standard as code in Browsertrix's frontend.

src/appmain.ts

@@ -646,6 +646,8 @@ export class ReplayWebApp extends LitElement {
 
   onStartLoad(event) {
     // just redirect right away?
+    // TODO: Fix this the next time the file is edited.
+    // eslint-disable-next-line @typescript-eslint/no-unsafe-argument
     this.pageParams.set("source", event.detail.sourceUrl);
 
     const url = new URL(window.location.href);
@@ -678,6 +680,8 @@ export class ReplayWebApp extends LitElement {
     //this.initRoute();
 
     if (event.detail.sourceUrl !== this.sourceUrl) {
+      // TODO: Fix this the next time the file is edited.
+      // eslint-disable-next-line @typescript-eslint/no-unsafe-argument
       this.pageParams.set("source", event.detail.sourceUrl);
       window.location.search = this.pageParams.toString();
     }