Show menu items' corresponding keyboard shortcuts when applicable

Some menu items in eM Client don’t show their corresponding keyboard shortcuts. I think it’s useful for all menu items to show their keyboard shortcuts when they have them.

Some examples of menu items that don’t show their keyboard shortcuts are:
Main Window
Forward (Ctrl+F)
Move to Junk/Spam (Ctrl+J)

New E-mail Window
Send (Alt+S / Ctrl+S)
Insert Link (Ctrl+K)