No loading state for FileContributors components

[samajammin]

Describe the bug

As a result of #2713, the FileContributors component creates a jumpy interaction on page load.

To Reproduce
Steps to reproduce the behavior:

1. Go to a documentation / tutorial page
2. View jump in layout when component data loads

e.g. screencast:

Screen.Recording.2021-04-08.at.12.02.06.PM.mp4

Expected behavior

We should add a loading state, e.g. with a dummy avatar or at least keeping the component height consistent during loading state so the page layout doesn't jump. Will need to account for different screen sizes.

Screenshots

See above

Desktop (please complete the following information):

All

Smartphone (please complete the following information):

All

Additional context

I believe we can also remove gatsby-source-graphql now that we're fetching Github data client-side?
https://github.com/ethereum/ethereum-org-website/blob/dev/gatsby-config.js#L223

Want to contribute?

We love contributions from the Ethereum community! Please comment on an issue if you're interested in helping out with a PR.

[hueyhe]

Hi, I'm new to the project and interested in contributing. I think we can solve this problem by adding a placeholder avatar with a fixed height. Can I work on this issue?

[ryancreatescopy]

Go for it! Assigned to you @hueyhe

[hueyhe]

@ryancreatescopy I've submitted a PR. Please comment if there's any problem.