The new "Open With..." command is visible on folders

[safisa]

Bug Description:

Hi,
The new updated "Open With..." command is visible on folders, only after being shown over files. It should not be visible over folders at all.

Related to this PR:
#13573

Steps to Reproduce:

1. Run Theia browser sample
2. right-click on any file in the files explorer (you need to do this step) to see the open with command
3. now right-click on any folder, and you will see the open with command too!

Additional Information

• Operating System: mac
• Theia Version: 1.49.0

[dhuebner]

@safisa
In Electron app you can use "Open with System Editor" and it will open the folder in your system file browser, that is handy! :)