(chocolatey#3381) Add new rule command

This adds a new command called ´rule` with an alias of `rules` to be
able to view any Validation Rules that have been implemented by
Chocolatey CLI, or the details of a specific view.

This allows a user to see what is implemented when they are packaging
their Chocolatey CLI package. This is intended to be used in the future
to enhance other functionality.

src/chocolatey.tests/chocolatey.tests.csproj

@@ -168,6 +168,7 @@
  <Compile Include="infrastructure.app\commands\ChocolateyListCommandSpecs.cs" />
  <Compile Include="infrastructure.app\commands\ChocolateyApiKeyCommandSpecs.cs" />
  <Compile Include="infrastructure.app\commands\ChocolateyConfigCommandSpecs.cs" />
+ <Compile Include="infrastructure.app\commands\ChocolateyRuleCommandSpecs.cs" />
  <Compile Include="infrastructure.app\commands\ChocolateyTemplateCommandSpecs.cs" />
  <Compile Include="infrastructure.app\commands\ChocolateyExportCommandSpecs.cs" />
  <Compile Include="infrastructure.app\commands\ChocolateyFeatureCommandSpecs.cs" />