add Catppuccin theme extension

[nekowinston]

Adds Catppuccin for Azure Data Studio to both extensionsGallery and extensionsGallery-insider.
It's pulling from our VSCode theme, but the VSIX is a special build for ADS.

[github-actions]

MSFT Gallery Maintainer Only
This is a reminder to update the Extensions Gallery list at https://github.com/Microsoft/azuredatastudio/wiki/List-of-Extensions once this PR has been merged in.
Instructions for doing this can be found here.

[nekowinston]

@microsoft-github-policy-service agree

[Charles-Gagnon]

Hey @nekowinston, thanks for your contribution! We'd love to get this added, but unfortunately at this time we don't allow direct VSIX installs from external sources. So you'll need to replace the Microsoft.VisualStudio.Services.VSIXPackage value with Microsoft.SQLOps.DownloadPage

e.g. https://github.com/microsoft/azuredatastudio/blob/release/extensions/extensionsGallery.json#L206

You will also need to update the count at the bottom of the file (increase it by 1) : https://github.com/microsoft/azuredatastudio/blob/release/extensions/extensionsGallery.json#L5281

[nekowinston]

Thanks! 😄