specify remote when adding file to dvc repo

Currently, one can add a file to dvc via dvc add some.file which will create a tracking file some.file.dvc. In this tracking file, one can add remote: some_remote to the fields, to tell dvc which remote to synchronize with (cf. docs). I would like to be able to do that from the command line per some argument to dvc add. The command already has argument -r/--remote (although currently only allowed in combination with --to-remote. It'd be great if it could be used for this purpose.

What I'm suggesting in code:
dvc add test.txt --remote foo should yield a file with this content

outs:
- md5: <SOME_HASH>
  size: <SOME_SIZE>
  path: test.txt
  remote: foo

Start by locating the implementation and tests for the dvc add command, especially its existing --remote handling with --to-remote. Trace how command options become the .dvc YAML output, then verify that dvc add test.txt --remote foo records remote: foo while existing behavior remains unchanged.