Bugfix/restore missing menus

[s0ph0s-dog]

This PR aims to bring the menu structure more in line with how typical Mac app menus look. I made the following changes:

• Brought back the Services menu (Telegram → Services)
• Brought back the Help menu
• Put Check for Updates… underneath About Telegram, where it is in other applications
• Moved Hide (Close) to the Window menu, where it belongs
• Moved Quick Search to a new Chats menu, which makes more sense than putting it under Telegram

This will require additional translation strings for:

• Services
• Help
• Telegram Help
• Chats

I don't think I broke anything, but I'm not entirely sure. Please test and let me know if I have to fix something!

[s0ph0s-dog]

@overtake Same here, please let me know what you think so I can make changes or move on.

[LIJI32]

Any updates on this PR? I'd love to see it merged.

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