[MM-22239] Add downloads dropdown

[tboulis]

Summary

TBA

Ticket Link

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Checklist

• [x] Added or updated unit tests (required for all new features)
• [x] Has UI changes
• [x] read and understood our Contributing Guidelines
• [x] completed Mattermost Contributor Agreement
• [ ] executed npm run lint:js for proper code formatting

Device Information

This PR was tested on: TBA

Screenshots

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Release Note

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[mm-cloud-bot]

@tboulis: Adding the "do-not-merge/release-note-label-needed" label because no release-note block was detected, please follow our release note process to remove it.

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[mattermod]

Hello @tboulis,

Thanks for your pull request! A Core Committer will review your pull request soon. For code contributions, you can learn more about the review process here.

[mattermod]

This PR has been automatically labelled "stale" because it hasn't had recent activity. A core team member will check in on the status of the PR to help with questions. Thank you for your contribution!

[tboulis]

I'll create a new branch + PR for this