v4.0.0: .NET 8 upgrade, Bootstrap v5

• Upgraded to .NET 8
• Upgraded to Bootstrap v5
• Fix encrypted files not sending their file length
• Removed jQuery
• Implement Serilog logging

OpenID Connect support; styling upgrade

Additional features:

• Styling upgrade
• OpenID Connect support (connect to Google, Windows Server ADFS)
• Fail2ban: Automatically fail after too many login attempts
• Server-side encryption of files using password