[Feature Request] Add more keyboard shortcuts

[hyuri]

For:

• Toggle (Hide/Show) Left Panel — Ctrl + F10?
• Toggle (Hide/Show) Right Panel (see also: #130) — Ctrl + F12?
• Toggle Focus Mode (see also: #131) — Ctrl + F11?
• Add Bookmark — Ctrl + Shift + B?
• Trigger the Context Menu — Menu & Shift + F10. See also: #91

And more.