Add JupyterLab Dark theme galata snapshots to (at least) Documentation/debugger, documentation/general, jupyterlab/collapsible-headings, jupyterlab/debugger, jupyterlab/texteditor

[andrii-i]

Description

Documentation/debugger, documentation/general, jupyterlab/collapsible-headings, jupyterlab/debugger, jupyterlab/texteditor don't have JupyterLab Dark galata snapshot tests to make sure there are no regressions in regards to changes from #14269 that ensures sufficient text contrast level of code line numbers.

It could be useful to add a snapshot test using dark mode to avoid regressions (could be a follow-up PR).

Originally posted by @krassowski in #14269 (review)

Reproduce

Note absence of JupyterLab Dark galata snapshots

[hxrshxz]

am i supposed to make separate files for the tests or add tests to the existing files?
for eg -
@JasonWeill

src/
|-- components/
|   |-- Debugger/
|   |   |-- Debugger.tsx          # Main component
|   |   |-- DebuggerDark.tsx      # Dark mode variant
|   |   |-- Debugger.test.ts      # Tests for Debugger.tsx
|   |   |-- DebuggerDark.test.ts  # Tests for DebuggerDark.tsx

or Add changes to the existing ?