Fix scroll in Sidebar component

[rheactdev]

If there are a lot of subscriptions, the part of the sidebar with subscriptions should scroll. But currently, the entire sidebar scrolls. This should be fixed so that the "Subscriptions" heading & settings menu are always visible.

[paratha14]

Would like to work on this issue kindly assign this to me

[rheactdev]

Go for it, let me know if you need any help setting up the project!