Bump webpack-dev-middleware, grunt-webpack and webpack-dev-server

Removes [webpack-dev-middleware](https://github.com/webpack/webpack-dev-middleware). It's no longer used after updating ancestor dependencies [webpack-dev-middleware](https://github.com/webpack/webpack-dev-middleware), [grunt-webpack](https://github.com/webpack-contrib/grunt-webpack) and [webpack-dev-server](https://github.com/webpack/webpack-dev-server). These dependencies need to be updated together.


Removes `webpack-dev-middleware`

Updates `grunt-webpack` from 1.0.18 to 7.0.0
- [Release notes](https://github.com/webpack-contrib/grunt-webpack/releases)
- [Commits](webpack-contrib/grunt-webpack@v1.0.18...v7.0.0)

Updates `webpack-dev-server` from 1.16.5 to 5.2.0
- [Release notes](https://github.com/webpack/webpack-dev-server/releases)
- [Changelog](https://github.com/webpack/webpack-dev-server/blob/master/CHANGELOG.md)
- [Commits](webpack/webpack-dev-server@v1.16.5...v5.2.0)

---
updated-dependencies:
- dependency-name: webpack-dev-middleware
  dependency-type: indirect
- dependency-name: grunt-webpack
  dependency-type: direct:development
- dependency-name: webpack-dev-server
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>