CORE-3721 Updated FileUploadDialogPanel layout.

Removed the borders around the simple upload form fields and reduced their height.
Moved the success/busy status for simple upload form fields to the right of their buttons.
Re-added the "upload destination" header to the URL import form panel.(cherry picked from commit 88fea77c1c9bbe723bdf11a6eda69fd250464574)
CORE-3855 Refresh data panel after simple upload.(cherry picked from commit 883cbfbc7976e1a6c38dbf996395f0ed66be7b46)
CORE-3753 Fixed validation in simple upload and URL import form.

Refactored the isValidFilename method into a isValidUploadField method that checks the upload TextField's validation in addition to checking for an empty filename.
Removed the logic to disable invalid upload/URL fields, since disabled fields always validate and those field values are now submitted separately rather than all at once by a parent form.(cherry picked from commit 9aba6d5742c40643b193f1ca1e0682e6e6d78358)
CORE-3753 Fixes for simple upload validation.

Removed the validateForm call from the FileUploadField Valid and Invalid listeners (the Invalid listener was causing a stack-overflow).
Added validateForm calls to the FileUploadField OnChange listener and the Reset button listener.
Updated the FileUploadField OnChange listener to specifically remove the "C:\fakepath\" string that Chrome adds to filenames in this field, since an invalid filename may contain invalid characters followed by a "/" or "\" that would all be removed, then the filename could pass validation after it was changed.
Removed extra filename.replaceAll calls, since these filename characters would already be removed by the OnChange listener.(cherry picked from commit bd6d9f02832c54da566e0ba2add1fbca00226e14)