vscode: support for workbench.sideBar

[abkein]

Description

Currently stylix doesn't change sidebar font and its size (file explorer).
Relevant settings:

workbench.sideBar.fontFamily
workbench.sideBar.fontSize

Submission Checklist

• I assert that this issue is relevant to Stylix
• I assert that this is not a duplicate of an existing issue

Notify maintainers

@Flameopathic
@danth

[trueNAHO]

Currently stylix doesn't change sidebar font and its size (file explorer).
Relevant settings:

workbench.sideBar.fontFamily
workbench.sideBar.fontSize

Feel free to submit a PR, if this is everything that is required.