[pgAdmin][RM6207] Update JS dependencies

Hi Hackers,

Attached is the patch to update the JS dependencies to latest. Changes
include:
1) Migrate from webpack 4 to webpack 5. This had a lot of breaking changes,
so updated multiple webpack plugins and changed the config accordingly.
2) Replaced iconfont-webpack-plugin with a more maintained webfonts-loader.
3) Replaced deprecated babel-eslint with @babel/eslint-parser
4) Replaced optimize-css-assets-webpack-plugin with a more maintained
css-minimizer-webpack-plugin
5) Updated all other JS packages and made the required code changes.

Note, there is an update available for slickgrid and I tried to update it.
But it was not working as expected. So without wasting time, I've not
updated slickgrid, and can be updated as a separate task.

Please review.

--
Thanks,
Aditya Toshniwal
pgAdmin hacker | Sr. Software Engineer | *edbpostgres.com*
<http://edbpostgres.com>
"Don't Complain about Heat, Plant a TREE"