Sidebar modifications

[gorkem-bwl]

We need 3 modifications on the sidebar.

• Sidebar should have full height and be sticky
• Sidebar - Other > Add link for "Discord channel" (link should go to https://discord.com/invite/NAb6H3UTjK)
• Sidebar - Other > Add link for "Support forum" (link should go to https://github.com/bluewave-labs/checkmate/discussions)
• SIdebar - Other > Settings should be moved to top level as it shouldn't be a part of "Other". Other category will be at the very bottom, and Settings will have its own top sidebar entry just over "Other" category.
• Sidebar - For all the links going to a 3rd party site (e.g external links), add an icon when the mouse is hovered on them. This icon can be used (but the icon design should be matching other icon designs, and possible be a little smaller).