[Dapp] Pin webpack-cli to version 3.3.0

[franckc]

Description:

New version of some webpack npms were recently released and that caused our DApp to fail to start locally with the error: "Error: Cannot find module 'webpack-cli/bin/config-yargs"

The issue was that while some of the webpack npms are pinned to a specific version in package.json, others were not.

This PR pins all the webpack packages to the current most recent stable version to avoid such issue in the future. I tested locally and was able to start the DApp with this config.

Alternatively, we could always use most the recent versions. Please comment if you think it is better - I don't have much history on why we decided to pin only some versions and not others :)

Checklist:

• Test your work and double-check to confirm that you didn't break anything
• Wrap any new text/strings with fbt for translation
• If there are any new/changed strings to translate, npm run translate
• Update any relevant READMEs and docs

[franckc]

Chatted with Nick. He had pinned webpack-dev-server to 3.2.1 due to this bug: webpack/webpack-dev-server#1777
This issue was recently fixed in webpack/webpack-dev-server@58d1682#diff-bd664d218d585ff7bd6ceced46bd877aL229 but unfortunately the fix did not make it in the most recent release.

For now, pinning webpack-cli to previous stable version 3.3.0 that is compatible with webpack-dev-server 3.2.1 and once issue above is fixed we can upgrade both webpack-cli and webpack-dev-server...