dvc status -c should probably exit with non-zero code if some files are not presented neither in cache, neither in remote.

It is possible that some files are not presented neither in local cache, neither in remote. In this case dvc status -c will print out warning and exit with zero code:

$dvc status -c
WARNING: Some of the cache files do not exist neither locally nor on remote. Missing cache files:
name: data.csv, md5: 746308829575e17c3331bbcb00c0898b
Data and pipelines are up to date.

It may happen if Alice executes dvc add data.csv, git add data.csv, git commit and git push but doesn't execute dvc push and Bob executes dvc status -c data.csv on another machine.

There should be a way in such case to exit with non-zero from dvc status command. It will allow to handle such errors in different scripts.

Context: https://discordapp.com/channels/485586884165107732/563406153334128681/743159360745898044