Better handle passphrase protected SSH keys

[jtpio]

Description

When using jupyterlab-git on a system for which the main SSH key is passphrase protected, jupyterlab-git may become unusable even when using it locally only.

jupyterlab-git-stuck.webm

Reproduce

Expected behavior

There should be a more informative error in the UI that jupyterlab git is not able to perform operations with the remote.

Ideally jupyterlab-git should also just work locally without having to need the SSK key.

Context

• Python package version: 0.50.1

• Extension version: 0.50.1

• Git version: 2.46.2

• Operating System and its version: