Allow to continue adding changed files to the review even if some of them are missing (SVN)

Submitting on behalf of Fidessa LatentZero

When adding changed files(Add Changes...), if any file is missing from the workspace it shows the message below and does not allow to continue with the rest of the files that are not missing.

The user is aware of that updating the workspace resolves the issue, but updating/scanning everything should be optional since it may take a long time and the missing files may not be longer needed.