"wait" CLI argument

When configuring fleet as the default VISUAL/EDITOR in e.g. `.zshrc` it is properly used for e.g. editing commit messages in git.

However, git doesn't wait for the editor to close the commit edit file as there is no `-w` (or similar, it's -w in VSCode) flag which would launch fleet in blocking mode and wait for the opened file to be closed before continuing.

See VSCode docs for a description of the according flag in VSCode.