Initial implementation of FTUE user lists design

This covers the "recents" section and rough design exclusively. It is known that the Field does nothing and that there's a bunch of missing functionality - this is to be iterated upon in future PRs. Labs flag is to aide development and should be removed in a very near future PR.

Also, this is focusing on DMs and not user lists in general because I misinterpreted the scope. I'll fix this in a future PR and instead make this the best DM invite dialog it can be.

Closes https://github.com/vector-im/riot-web/issues/11197

package.json

@@ -74,7 +74,6 @@
     "file-saver": "^1.3.3",
     "filesize": "3.5.6",
     "flux": "2.1.1",
-    "react-focus-lock": "^2.2.1",
     "focus-visible": "^5.0.2",
     "fuse.js": "^2.2.0",
     "gemini-scrollbar": "github:matrix-org/gemini-scrollbar#91e1e566",
@@ -82,6 +81,7 @@
     "glob": "^5.0.14",
     "glob-to-regexp": "^0.4.1",
     "highlight.js": "^9.15.8",
+    "humanize": "^0.0.9",
     "is-ip": "^2.0.0",
     "isomorphic-fetch": "^2.2.1",
     "linkifyjs": "^2.1.6",
@@ -99,6 +99,7 @@
     "react-addons-css-transition-group": "15.6.2",
     "react-beautiful-dnd": "^4.0.1",
     "react-dom": "^16.9.0",
+    "react-focus-lock": "^2.2.1",
     "react-gemini-scrollbar": "github:matrix-org/react-gemini-scrollbar#9cf17f63b7c0b0ec5f31df27da0f82f7238dc594",
     "resize-observer-polyfill": "^1.5.0",
     "sanitize-html": "^1.18.4",