Add CLI command to edit project meta information

[swissspidy]

Basically like https://github.com/wp-cli/entity-command, but for project meta, I'd want an easy way to set project meta information like VCS type and things like that using WP-CLI.

Not sure how easy it would be to require that command and extend \WP_CLI\CommandWithMeta. Otherwise we'd have to copy the code a bit.

Also, this might be something for GlotPress itself and not specifically Traduttore.