refactor(code-modal): use chakra modal with custom variant

[LuisUrrutia]

Description

Migrates CodeModal component from emotion to chakra-ui.

To do this change, I had to use the modal component from chakra-ui and adjust the zIndex of portals to 1001 (by default, it's 40) because the modal overlay was behind the header of the website (z-index: 1000).

The result's pretty close to the original, but it has some little differences (really minimal) to preserve most of the default values of chakra.

Related Issue

#6374

[LuisUrrutia]

I removed the className property because it wasn't used anywhere

[gatsby-cloud]

✅ ethereum-org-website-dev deploy preview ready

• Deploy preview
• Build logs · 32m build time

[pettinarip]

Hey @LuisUrrutia this is great! awesome work defining the new variant.

I've left a couple of questions and a few minor changes.

[pettinarip]

Internal: retriggered a rebuild and it was successful

[pettinarip]

Awesome @LuisUrrutia thanks for the work on this PR 💪🏼

Be sure to join the discord if you are interested in contributing further to the project or have any questions for the team. And we've just released our 2022 POAPs so remember to claim yours also 🥳!

[gitpoap-bot]

Woohoo, your important contribution to this open-source project has earned you a GitPOAP!

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[pettinarip]

@all-contributors please add @LuisUrrutia for code

[allcontributors]

@pettinarip

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