* Implemented File Download Experience
1. Initiate download manager when a file download is initiated.
2. Add items to download manager when new items are downloaded.
3. Allow user to open file in default OS app.
4. Allow user to show file in finder/explorer.
5. Allow user to close download bar.
* 1. Removed underscore
2. Added safety checks
3. Added support for popouts
4. Creating most elements of download manager if electron
* 1. Moved download manager logic to a separate file
* 1. Added styles to help pushing up the content of the app when the download manager is being shown.
* 1. Added tests for Download Manager.
* Removed unnecessary code.
* Made adjustments to handle positioning of the download manager through the flexbox model rather than the fixed positioning way.
* Removed data attributes being added to body to handle download manager.
