Add support for localization to the lab extension

[jtpio]

At the moment the "Save Widget State Automatically" command label is not translated when using JupyterLab in a different display language, in the following case in French:

This PR adds an optional ITranslator to the lab plugin to handle this.

We also use a custom jupyterlab_widgets domain since the extension lives outside of the core JupyterLab repo right now.

[github-actions]

👈 Launch a binder notebook on branch jtpio/ipywidgets/translator

[jtpio]

This can be backported to 7.x.

[vidartf]

This mostly looks good to me, but to make sure I understand: If a translator wanted to add an entry for this, would they add the entry to the same language pack that JupyterLab uses? How would the versioning of our keys compare to that of JupyterLab? I.e. if we change something, how will we ensure compatibility between an old ipywidgets version and new lab and/or new ipywidgets and old lab?

[jtpio]

Since jupyterlab_widgets is a regular lab extension, it can follow the same process as other extensions which are currently living in https://github.com/jupyterlab/language-packs

Also this is only for the lab extension and should be independent of the main ipywidgets package.

I've just opened jupyterlab/language-packs#109 to add jupyterlab_widgets to the list.

[krassowski]

If a translator wanted to add an entry for this, would they add the entry to the same language pack that JupyterLab uses.

Different translation file, the same language pack (may change in the future).

if we change something, how will we ensure compatibility between an old ipywidgets version and new lab and/or new ipywidgets and old lab?

Language packs will retain old translation strings for some time (we didn't decide on how long for extensions, but for JupyterLab as long as old versions are supported). This is tracked in jupyterlab/language-packs#43. I saw @fcollonval implement some of that in jupyterlab/jupyterlab-translate#9 but I think we are not confident that it all works on integration level just yet?

[fcollonval]

but I think we are not confident that it all works on integration level just yet?

Yep for now the merge of source strings is working. But there is no information about the version from which the strings are coming. So there is no easy way to handle the lifecycle of the source strings for extensions in the JupyterLab language packs.

[jasongrout]

Thanks for answering Vidar's question. Since this seems like the best we can do, I think we ought to go forward. Thanks!