Feedback for system and header

[siddharthkp]

• Button height should match Input height
• Match avatar in header to button height
• Add variant: link for select (figma)
• Add editor drop background in codesandbox theme
• stop overriding user menu buttons from new header

[lbogdan]

Build for latest commit 2dc1823 is at https://pr3547.build.csb.dev/s/new.

[SaraVieira]

guud, guuud