Don't require a body for comment PR reviews #399

fixes #372

gitea's ui also cant do that - this has to be canged everywhere ...

@6543 According to https://github.com/go-gitea/gitea/pull/16229 it does work, thus the change to the API was made.

 	// comment
 	var promptOpts survey.AskOpt
 	if state == gitea.ReviewStateComment || state == gitea.ReviewStateRequestChanges {
 	if (state == gitea.ReviewStateComment && len(codeComments) == 0) || state == gitea.ReviewStateRequestChanges {