[legacy-framework] Update eslint to v7 in new app template and the blitz repo

[pragmaticivan]

Closes: blitz-js/legacy-framework#661
Address the root migration part of blitz-js/legacy-framework#661.

What are the changes and their implications?

This PR updates eslint to v7.x.
Follows new recommendation for V7 migration: https://eslint.org/docs/user-guide/migrating-to-7.0.0#default-ignore-patterns
It currently ignores dotfiles but not .eslintrc.js

Checklist

• Tests added for changes

[pragmaticivan]

cc @nettofarah

[flybayer]

@pragmaticivan so sorry for the long delay here!

Thank you so much!! Looks good, I just have one question.

[flybayer]

Ok now there's a yarn.lock conflict that needs resolved, and then we can merge!

Note: this doesn't fully close blitz-js/legacy-framework#661, the one remaining item is to update the eslint and plugin versions in the new app template. If you want to tackle that issue too, you can add that to this PR or do it as a separate PR. Up to you. And of course you can leave it for someone else to do. :)

[pragmaticivan]

hi @flybayer, I just fixed the conflicts, rebased the PR, and added the update on template app.

[flybayer]

@pragmaticivan awesome! One final thing which I think you might have overlooked in my last comment, is to also update the eslint plugins in the new app template package.json.

[pragmaticivan]

hi @flybayer you meant this change?

[flybayer]

Yes, this is good, but we also need to update the other eslint-* packages in this file

[pragmaticivan]

Do you think it would be also worth updating?:

 @typescript-eslint/eslint-plugin                           2.x  →      3.x
 @typescript-eslint/parser                                  2.x  →      3.x

[flybayer]

yes! All the eslint related packages

[pragmaticivan]

done, thanks!

[flybayer]

Awesome, I tested and it works great. Thank you so much!!

@all-contributors add @pragmaticivan for code

[allcontributors]

@flybayer

I've put up a pull request to add @pragmaticivan! 🎉