Add command to change a key's value

[Boscop]

🚀 Feature Proposal

Add command to change a key's value for a given language.

Motivation

It's much faster to run a CLI command than to login to locize's UI to change a key's value.
And it allows bulk changes much easier.

[adrai]

Should be already possible with the add command: https://github.com/locize/locize-cli#addingupdating-new-keys

[Boscop]

Ah, I didn't know that add also updates.
Because I looked at locize add --help which didn't show that it accepts --update-values true.