Add support to the migrate tool for more types of breaking changes

[edmorley]

In #1246 a new migrate tool (@neutrinojs/migrate) was added. This tool currently only knows how to apply the .neutrinorc.js changes required by #1246, so it would be good to also add support for:

• creating the webpack.config.js, .eslintrc.js, ... template files
• adding the new webpack/eslint/... dependencies to the project's package.json
• update the package.json scripts to use the new recommended values
• warning if using presets that were removed in v9
• ...

There will be quite a bit of overlap with create-project - I wonder if the two should be combined or should use a common config library?

[edmorley]

Probably not worth it now.