Improve "VS Code Extensions" sections in Languages & Frameworks guides

[jankeromnes]

In our Languages & Framework guides, we typically suggest various popular VS Code Extensions for each language or framework, e.g.:

• https://www.gitpod.io/docs/languages/python/#vscode-extensions
• https://www.gitpod.io/docs/languages/java/#vscode-extensions
• https://www.gitpod.io/docs/languages/go/#vscode-extensions
• https://www.gitpod.io/docs/languages/bash/#vscode-extensions
• https://www.gitpod.io/docs/languages/ruby/#vscode-extensions
• https://www.gitpod.io/docs/languages/vue/#vscode-extensions
• https://www.gitpod.io/docs/languages/svelte/#vscode-extensions
• https://www.gitpod.io/docs/languages/scala/#vscode-extensions
• https://www.gitpod.io/docs/languages/rust/#vscode-extensions
• https://www.gitpod.io/docs/languages/dotnet/#useful-vscode-extensions
• https://www.gitpod.io/docs/languages/dart/#vscode-extensions
• https://www.gitpod.io/docs/languages/latex/#vscode-extensions
• https://www.gitpod.io/docs/languages/r/#vscode-extensions
• https://www.gitpod.io/docs/languages/deno/#vscode-extensions

However, there is currently a lot of repetition in these sections. It would be nice to have a simpler / more streamlined way to present popular extensions, and factor out the instructions on how they should be installed.

Suggested here: https://github.com/gitpod-io/website/pull/971#discussion_r566650852 (thread)