Drop-send multiple files➬ask for all files at once

[Simon-Laux]

fixes #1622

[Jikstra]

I think for something like this functional patterns come in very handy.

Just some pseudo code

let fileList: FileList = (e.target as any).files || e.dataTransfer.files
const forbiddenPathRegEx = /DeltaChat\/.+?\.sqlite-blobs\//gi
const isForbidden = ({path, name}) => {
  if(forbiddenPathRegEx.test(path.replace('\\', '/'))) {
    log.warn('Prevented a file from being send again while dragging it out', name)
    return false
  }
  return true
}
const sanitizedFileList = fileList.filter(isForbidden)

[Simon-Laux]

nah, we can still change this later..
PS: I used a feature of let here, scoped usage. might have interesting usages.

[Jikstra]

I think functional patterns would be nicer but anyway this looks good.