Modernisation and bug-fixes

[las-nsc]

• Upgrade project format to SDK-style
• Fix Sharp.Xmpp references and added missing Extension enum values
• Apply code style suggestions throughout project
  • Removed event Raise extension method, in favour of built-in ?.Invoke
  • Replaced ThrowIfNull strings with nameof equivalent (fixed some mistakes)
• Enabled NRT and C#9, fixed all NRT warnings
  • Replaced string.IsNullOrEmpty and string.IsNullOrWhitespace with NRT-friendly alternatives
  • Changed XmppCore and XmppIm to initialise and connect upon construction to simplify nullability of some variables
  • Changed XmppIm extension construction to use simple dependency resolution to simplify nullability of some variables
  • Added guards for various variables which were being used when potentially null
  • Throw exception when getting missing XML-derived property values to avoid nullability
• Removed constructors for XmppCore and XmppIm without username and password as they make no sense.
• Made JID equality check case insensitive
• Added retry for send/receive of IQ request/response, since sometimes it was timing out (restored exception).

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
No Duplication information