ECMS-6497 | [CKEditor] [Insert Image] Missing "Upload file" button in Co...

...ntent Selector form

*Problem Analysis:*
* The `filterAreaID` where the upload button should be appended is hidden whenver file type is an image.
* Fitler and upload labels are not internationalized.

*Fix Description:*
* Hide only filter area (holding filter label and filter dropdown list) to keep upload button shown.
* Use localized labels for filter and upload from `UserLanguage`.