[macOS] move Pester tests to separate files/contexts/describes (#2573)

* [macOS] Fail Pester tests on error

* return it back

* added all files for testing

* common utils path changed

* linux scripts shouldn't be touched

images/macos/tests/Git.Tests.ps1

@@ -0,0 +1,13 @@
+Describe "Git" {
+    It "git is installed" {
+        "git --version" | Should -ReturnZeroExitCode
+    }
+
+    It "git lfs is installed" {
+        "git lfs version" | Should -ReturnZeroExitCode
+    }
+
+    It "hub CLI is installed" {
+        "hub --version" | Should -ReturnZeroExitCode
+    }
+}