* [refactor] Introduce a file download service
* [refactor] Point platformUtilsService.saveFile() callers to fileDownloadService.download() instead
* [refactor] Remove platformUtilsService.saveFile()
* [fix] Force send attachments to always download and never open
* [fix] Remove the window property from FileDownloadRequest
* [fix] Move FileDownloadRequest to /abstractions/fileDownload
* [fix] Simplify FileDownloadRequest to a type
* [fix] Move BrowserApi.saveFile logic into BrowserFileDownloadService
* [fix] Use proper blob types for file downloads
* [fix] forceDownload -> downloadMethod on FileDownloadRequest
* [fix] Remove fileType from FileDownloadRequest
* [fix] Make fileType private