GUACAMOLE-1859: Update to latest compatible versions of JavaScript dependencies.

The Pickr library also has an update (v1.9.0), but that update does not
successfully build, possibly due to a different level of JavaScript
version compatibility.

doc/licenses/webpack-4.47.0/LICENSE

@@ -0,0 +1,20 @@
+Copyright JS Foundation and other contributors
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+'Software'), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

doc/licenses/webpack-4.47.0/README

@@ -0,0 +1,8 @@
+Webpack (https://webpack.js.org/)
+---------------------------------
+
+    Version: 4.47.0
+    From: 'JS Foundation and other contributors'
+    License(s):
+        MIT (bundled/webpack-4.47.0/LICENSE)
+

doc/licenses/webpack-4.47.0/dep-coordinates.txt

@@ -0,0 +1 @@
+webpack:4.47.0