Typescript config parity with Browsertrix repo (#289)

Follow-up from #288 

This matches the strictness rules with the Browsertrix repo,
specifically `noImplicitAny`, and then adds `// @ts-expect-error`s to
suppress existing errors this change raises. This'll help us keep code
quality high moving forward.

Going to just directly merge this once it passes CI; as with #288, this
doesn't change any code, just comments.

src/item-info.ts

@@ -240,6 +240,7 @@ class ItemInfo extends LitElement {
     return false;
   }
 
+  // @ts-expect-error [// TODO: Fix this the next time the file is edited.] - TS7006 - Parameter 'reload' implicitly has an 'any' type.
   onPurge(reload) {
     const detail = { reload };
     this.dispatchEvent(new CustomEvent("item-purge", { detail }));