Allow dep ensure -add and -update when lock is out-of-sync

[ibrasho]

#1109 changed the error message printed when the lock file is out-of-sync with the manifest and the project's imports.

This error seems a bit strict and we want to allow the user to use dep ensure -add and dep ensure -update even when things are out-of-sync. The error should be printed as a warning instead, but execution should resume.

The changes should happen to the same files modified in #1109.

[ibrasho]

cc: @akutz

[7373Lacym]

I would like to work on this if possible.

[ibrasho]

Go for it. 👍

Let me know if you need any pointers.

[sdboyer]

@7373Lacym it's been near two weeks - are you still planning on working on this? it's fine if not, but it'd be ideal if you could update this issue if you don't have time, so that other folks feel comfortable claiming it.

[miguel250]

@carolynvs mentioned that this was up for grabs so I am taking it.

[7373Lacym]

👍 Sounds good. Im not able to get to this.