fidelity: fix eval edge case (via wombat), enable http->https check for wacz sources (via wabac.js)

dependency updates:
- switch to webpack 5 and related build dependencies
- update litelement -> 'lit'
- wabac.js 2.9.2, wombat 1.3.4

search:
- update to latest flexsearch
- optimize search by using single-field index

bump to 1.5.3

src/embed.js

@@ -1,5 +1,5 @@
-import { LitElement, html, css } from "lit-element";
-import { ifDefined } from "lit-html/directives/if-defined.js";
+import { LitElement, html, css } from "lit";
+import { ifDefined } from "lit/directives/if-defined.js";
 
 import { registerSW } from "./pageutils";