* Move loadImageBase64 into DictionaryImporter
* Convert mediaUtility to a class
* Add getFileExtensionFromImageMediaType to MediaUtility
* Use MediaUtility instead of _getImageExtensionFromMediaType
* Use MediaUtility in ClipboardReader to validate images before reading
* Create ClipboardReader class
* Use ClipboardReader in Backend
* Update ClipboardMonitor to use ClipboardReader
* Replace _onApiClipboardImageGet call
* Assign clipboard reader browser