Epic: Improve Desktop IDE onboarding flow

[loujaybee]

Description TBD.

Related:

• Import SSH public keys from 3rd parties (GitHub, GitLab, BitBucket) #11370
• Prompt when desktop IDE not installed (or open), e.g. "scheme does not have a registered handler" #9975
• Epic: Reduce popups in VS Code Desktop flow #15920

[loujaybee]

@loujaybee to add more description updates and speak to @gtsiolis about designs.

[akosyakov]

#11370 is not relevant for VS Code Desktop if #16836 successful, only for general SSH

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.