Updates to Desktop App developer docs

[devinbinnie]

Summary

A few updates to the Developer docs for Desktop App:

• Updated the command list
• Removed reference to the MSI builder
• Added Dev tools for Calls widget
• Refined the packaging docs

Ticket Link

https://mattermost.atlassian.net/browse/MM-58223

[github-actions[bot]]

Newest code from devinbinnie has been published to preview environment for Git SHA 224449506934de9bdb59a76d71e34ecd587ce4f9