Replace current validates with pester testing approach #1 (#1253)

* first part

* fix session manager plugin

* rework AWS installation

* azure cosmos db tests

* azure devops cli

* add azmodules test

* put brackets

* add root folder

* remove validate aliyun

* add azure modules

* update modules test

* docker, baze, dotnetsdk

* DACFx

* add azdevopscli

* change to Should -BeTrue

* nitpicks

* remove extra

* add azurecli

* remove BeforeAll for DACFx

* a bit of refactoring

* fix templates

* remove disk space validation

* rename to powershell modules

* fix templates

images/win/scripts/Tests/DotnetSDK.Tests.ps1

@@ -0,0 +1,26 @@
+$releaseIndexUrl = "https://raw.githubusercontent.com/dotnet/core/master/release-notes/releases-index.json"
+$dotnetChannels = (New-Object system.net.webclient).DownloadString($releaseIndexUrl) | ConvertFrom-Json
+$dotnetVersions = $dotnetChannels.'releases-index' | Where-Object { (!$_."support-phase".Equals('preview') -and !$_."support-phase".Equals('eol')) } | Select-Object -ExpandProperty "channel-version"
+
+Describe "Dotnet SDK" {
+
+    Context "Default" {
+        It "Default Dotnet SDK is available" {
+            "dotnet --version" | Should -ReturnZeroExitCode
+        }
+    }
+
+    foreach ($version in $dotnetVersions) {
+        Context "Dotnet $version" {
+            $dotnet = @{ dotnetVersion = $version }
+
+            It "SDK $version is available" -TestCases $dotnet {
+                (dotnet --list-sdks | Where-Object { $_ -match "${dotnetVersion}\.[0-9]*" }).Count | Should -BeGreaterThan 0
+            }
+
+            It "Runtime $version is available" -TestCases $dotnet {
+                (dotnet --list-runtimes | Where-Object { $_ -match "${dotnetVersion}\.[0-9]*" }).Count | Should -BeGreaterThan 0
+            }
+        }
+    }
+}