Add linting tools and pre-commit Git hooks

[manumonti]

To standardize the code format and increase the code robustness, it's necessary to incorporate subgraph repo standard development guidelines.

The proposed tools are Prettier and ESLint:

• Added Yarn scripts to check and fix errors caught by these tools.
• Added pre-commit hooks to check format and code errors in each commit.
• Updated README file with a contributing field.

This is not a final decision about linting. Feel free to suggest prettier/linting rules. 😄

[theref]

All looks good, we might want to look at adding a github workflow for some of the linting as well, just to make sure that's it's being enforced. Not a blocker for now though.

[manumonti]

Looks good! 👍 Left a few comments to look at.

Let's add .git-blame-ignore-revs file to ignore bulk changes. Please see https://www.moxio.com/blog/43/ignoring-bulk-change-commits-with-git-blame. Unfortunately, it requires adding bulk change commits manually to the .git-blame-ignore-revs file but I believe ignoring bulk changes it's a good practice.

@r-czajkowski

Sure! I'm planning to make a new PR formatting the code with the new style once this PR is merged. There we can add .git-blame-ignore-revs file.

Thank you for the link! I have no idea about that was possible. 👍

I pushed some new commits with these changes:

• Use of Husky instead of pre-commit to set-up git hooks. In my opinion, Husky let us manage this in an easier way.
• Pre-commit strategy: When git commit, only prettier is run. When git push, prettier and eslint are run. This allows us to commit locally incomplete contributions, but only complete contributions (without errors) can be pushed to the remote repo.
• Added two prettier rules: line length to 80 char and use of semicolons at end of every statement not allowed.
• Yarn scripts for linting allow using prettier and eslint independently.

[manumonti]

I've added lint-staged and modified package scripts. @r-czajkowski can you check if you agree with this strategy?