Webpack improvements: remove "webpack-filter-warnings-plugin"

[prupipho]

Describe the issue
While updating to webpack5 in the extension we noticed a plugin that hasn´t been recently updated. Investigating a bit further we think it would be nice to get rid of it:

• "webpack-filter-warnings-plugin": "^1.2.1" (last updated time was 2 years ago (2019)
• See this recommendation too
  Package is used in extension\webpack.config.js