Address several static code analysis warnings

[skwasjer]

• fix(CA2007): ConfigureAwait the task
• style(CA1819): properties should not return arrays
• style(CA1037): overload accepting StringComparison
• style(CA8602): suppress dereference possible null
• style(CA2000): suppress because it is registered for dispose
• style(CA2201): suppress
• style(CA1859): change interface type to concrete type for perf.
• style(CA1054,CA1056): change type of parameter from string to Uri.
  • The MockHttpServer.HostUrl is deprecated. Use MockHttpServer.HostUri instead.
  • The MockHttpServer ctors accepting string URL's are deprecated. Use the overloads accepting System.Uri.
• style(CA1861): prefer 'static readonly' fields over constant array args.
• style(CA1860): prefer comparing count to 0 rather using Any()
• style(CA5394): do not use insecure randomness
• style(CA1307,CA1309): Use ordinal string comparison

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
3 Code Smells

92.7% Coverage
0.0% Duplication