'Upload a file...' button does not bring focus to the File picker

When you attempt to upload a file with an activity:

• Choose a file... button
• Opens the file picker

*Result:* Opens file picker but does not bring focus to File picker overlay. Tabbing continues moving through the DOM from last focused element (the choose a file button).

*Expected Result:* Focus is moved to the File picker overlay and subsequent tabs move the user through the File Picker

*Justification:* Blind/Keyboard users have to tab to the bottom of the document until they arrive at the File Picker. This is more of an issue to a Blind user who is not even informed that the File Picker overlay has appeared on screen. Proper use of focus() and ARIA roles should be used to bring focus to the new element and announce the appearance of the File picker.