[Rich Content Editor] focus to text area when find tray invoked

[Mikee]

Problem statement:

When I'm editing text and invoke the find tray [in my case with a keyboard shortcut that overrides the browser search function] I expect the entry field to be brought out in focus so I can type into it easily, and this matches other applications that I use, like Chrome and Word.

Proposed solution:

Set the focus in the find tray as the text entry field on invocation

User role(s):

admin,instructor,student,ta,designer,observer

[Mikee]

Having to click or tab into the text field to complete the action I invoked is nonsensical. 

Focus being on the close button also doesn't make sense when [esc] will close out the tray as well.