Add placeholder avatar to prevent layout jumping [Fixes #2809]

[hueyhe]

Description

Add placeholder avatar to prevent layout jumping [Fixes #2809]

[wackerow]

@hueyhe Hey, thanks for doing this! Was just looking at it, seems to work pretty well.

I'll defer to @ryancreatescopy on styling comments, then I'll be happy to double check the code and bring this in 👍🏻

[ryancreatescopy]

I think it'd be cool if we had a loading state for text and button too. Maybe something like this super rough sketch:

could even add some kind of light animation to it to suggest it's loading, it looks a little jerky right now.

[hueyhe]

@ryancreatescopy OK. I'll work on that.

[hueyhe]

@ryancreatescopy I've updated the skeleton style and added a transition from the loading state to loaded state.
FYI, I'm not good at picking colors. The skeleton might look a bit bright in dark mode. Please tell me if you have any suggestion.

[wackerow]

Added a commit using some of our theme colors instead, which respond to light and dark mode.

[wackerow]

@hueyhe I like how this is coming along! Noticed this causes a bug on mobile though, mind taking a look at that?
May just be a matter of hiding the contributors button until loading is done.

[hueyhe]

@wackerow I've fixed the bug on mobile. Please comment if there's any other problem.

[wackerow]

@hueyhe lookin good! Thanks for being patient, pulling in now =)

[wackerow]

@all-contributors please add @hueyhe for code

[allcontributors]

@wackerow

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