big ui update, page search + full text

- split file chooser from coll index, insert as header, make file chooser collapsible
- revamp collection index to be responsive
- add separate sorter component, used for collection index and pages
- combine 'curated lists' + pages, with page search + narrative
- ensure page + narrative lists are collapsible
- page search: support title, url and full text search if available, using flexsearch
- page search: keyword highlighting, load all pages, showing in increments of 100
- page and resource search: delay search to 1/4 sec of inactivity to avoid too many queries
- electron app: ensure noCache is set to true for local files
- embedding: remove separate embed.js, just use ui.js for embed as well
- embedding: support embedding iframe in a local origin with just sw.js and ui.js: sw.js serves index.html,
<replay-web-page> embed injects ui.js into iframe
- sw.js, new service worker entry point
- sw and ww inited only from <replay-app-main>, ui.js loaded from <replay-web-page> embed component

package.json

@@ -9,6 +9,8 @@
   "dependencies": {
     "@fortawesome/fontawesome-free": "^5.13.0",
     "bulma": "^0.8.2",
+    "flexsearch": "^0.6.32",
+    "keyword-mark-element": "^0.1.2",
     "lit-element": "^2.3.1",
     "marked": "^1.0.0",
     "mime-types": "^2.1.27",