Fix analyzer errors in Renci.SshNet and Renci.SshNet.TestTools.OpenSSH (#1229)

* Fix analyzer errors in Renci.SshNet and Renci.SshNet.TestTools.OpenSSH.
Suppress all errors in unit tests and integration tests.

* Update unit tests now that we pass 'mode' as argument name when we throw ArgumentException.

* Remove stale comment and add unit tests for SshData.ReadBytes(int length).

* Remove unnessary suppression.

* Remove Visual Studio magic.

* Removed duplicate source file.

* Clarified that suppression hides a false positive.

* Remove suppressions for S2372.

* Update ReadExtensionPair() to return concrete dictionary.

Directory.Build.props

@@ -18,7 +18,7 @@
         Code analysis properties.
     -->
     <PropertyGroup>
-        <EnableNETAnalyzers>false</EnableNETAnalyzers>
+        <EnableNETAnalyzers>true</EnableNETAnalyzers>
         <AnalysisLevel>preview-All</AnalysisLevel>
         <EnforceCodeStyleInBuild>true</EnforceCodeStyleInBuild>
     </PropertyGroup>
@@ -34,11 +34,9 @@
         Use fixed version of analyzers.
     -->
     <ItemGroup>
-        <!--
         <PackageReference Include="Microsoft.CodeAnalysis.NetAnalyzers" Version="8.0.0-preview1.23165.1" PrivateAssets="all" />
         <PackageReference Include="StyleCop.Analyzers" Version="1.2.0-beta.435" PrivateAssets="all" />
-        <PackageReference Include="Meziantou.Analyzer" Version="2.0.54" PrivateAssets="all" />
-        <PackageReference Include="SonarAnalyzer.CSharp" Version="8.55.0.65544" PrivateAssets="all" />
-        -->        
+        <PackageReference Include="Meziantou.Analyzer" Version="2.0.103" PrivateAssets="all" />
+        <PackageReference Include="SonarAnalyzer.CSharp" Version="9.12.0.78982" PrivateAssets="all" />
     </ItemGroup>
 </Project>