Add WebIDE and Gitpod buttons to Compact Code Dropdown

What does this MR do and why?

Add WebIDE and Gitpod buttons to Compact Code Dropdown

This feature is behind "directory_code_dropdown_updates" feature flag

References

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• see this note for design
• third part #450667 (closed). implementation plan for the whole issue is here

MR acceptance checklist

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	directory_code_dropdown_updates flag OFF	directory_code_dropdown_updates flag ON
directory	🗒️ : the edit button does not show here as there're no longer any items under it. the your workspaces section is being worked on in #513135 (closed)
blob	🗒️ : no change in this view. both buttons remain in blob edit dropdown.
project overview
mobile	🗒️ : the layout here is different from final design. those will be worked on in separate MRs.

How to set up and validate locally

1. Enable directory_code_dropdown_updates and blob_repository_vue_header_app feature flag

      Feature.enable(:directory_code_dropdown_updates)
      Feature.enable(:blob_repository_vue_header_app)

2. Select a directory

3. Select a file

4. WebIDE should open either a) Select WebIDE in dropdown b) Shortcut .

5. Enable Gitpod for both the instance and user, Gitpod should render the dropdown and can be opened by selecting Gitpod

Related to #450667 (closed)

Resolves #513135 (closed)