Update 0.59.x to latest brave-ui 0.59.x

Fix brave/brave-browser#2439 - Clock AM / PM font size
Use brave-ui welcome images instead of brave-core

```
*   4e07f89 - (59 minutes ago) Merge pull request #315 from brave/revert-sync-59 — Pete Miller (HEAD -> brave-core-0.59.x, origin/brave-core-0.59.x)
|\
| * fb7deb8 - (69 minutes ago) Revert "sync v2" — Cezar Augusto
| * c5e16c7 - (69 minutes ago) Revert "Merge pull request #308 from brave/sync_img" — Cezar Augusto
|/
* c4694e2 - (20 hours ago) Merge pull request #247 from brave/c71-clock-period — Pete Miller
* a2443d8 - (4 days ago) do not count first letter if space in textareaclipboard — Cezar Augusto
* 2c16ae2 - (5 days ago) Merge pull request #308 from brave/sync_img — Cezar Augusto
* 7d9811c - (3 weeks ago) sync v2 — Cezar Augusto
* 3e3be2f - (4 days ago) update snapshot from walletSummary — Cezar Augusto
* a4c4dbd - (5 days ago) Merge pull request #309 from brave/welcome_img — Pete Miller
```

package.json

@@ -272,7 +272,7 @@
     "@types/react-dom": "^16.0.7",
     "@types/react-redux": "6.0.4",
     "awesome-typescript-loader": "^5.2.0",
-    "brave-ui": "brave/brave-ui#9be9bee9764c6a1fd329acbe348f91b85142dc33",
+    "brave-ui": "brave/brave-ui#4e07f892a38e588d9dbca8dfa9d39fe06642183f",
     "css-loader": "^0.28.9",
     "csstype": "^2.5.5",
     "emptykit.css": "^1.0.1",