Audit selectKernel dialog to make sure it always has translator

[JessicaBarh]

Description

"Select Kernel" dialog does not display in selected UI language.
the options.translator seems to be null in:

jupyterlab/packages/apputils/src/sessioncontext.tsx

Line 320 in dd73fa3

this.translator = options.translator || nullTranslator;

Reproduce

1. Go to File -> New -> Notebook
2. "Select Kernel" dialog comes up

Expected behavior

This is the dialog displayed working correctly if opened by clicking on the kernel name at the top right corner of a notebook:

Context

• JupyterLab version: 3.0.11

[jasongrout]

It does look like there are a few places that selectKernel is being called without a translator: https://github.com/jupyterlab/jupyterlab/search?q=selectKernel%28

[jasongrout]

My guess is the place you are seeing is from

jupyterlab/packages/docregistry/src/context.ts

Line 496 in 36db8f7

void this._dialogs.selectKernel(this.sessionContext);

You could verify it by setting a breakpoint and looking at the stack trace, to see who is calling selectKernel without a translator argument.

[SRILEKHA-V19]

I can take a look at this issue and give it a try :)
(Beginner at open source contribution to a large community using this tool)

[fcollonval]

Fix was included in #12858