ci(): Add code formatter (#24)

Add a script to format the scripts using Invoke-Formatter and Edit-DTWBeautifyScript.

Author: donny-dont

.gitignore

@@ -0,0 +1,2 @@
+# Downloaded PS Modules
+/psmodules/

Invoke-Formatter.ps1

@@ -0,0 +1,75 @@
+param(
+    [switch]$exitCodeOnFormat = $false,
+    [string]$moduleRoot
+)
+
+$ErrorActionPreference = 'Stop';
+
+# Import the PowerShell modules locally
+if (-not ($moduleRoot)) {
+    $moduleRoot = Join-Path $PSScriptRoot -ChildPath 'psmodules';
+}
+
+if (-not (Test-Path -Path $moduleRoot)) {
+    New-Item -Path $moduleRoot -ItemType 'directory' | Out-Null;
+}
+
+function Import-ModuleLocally {
+    param(
+        [string]$name,
+        [string]$version
+    )
+
+    Write-Information -MessageData ('Importing {0} v{1}' -f $name,$version) -InformationAction Continue;
+    if (Get-Module -Name $name) {
+        Remove-Module -Name $name;
+    }
+
+    $importModule = Join-Path $moduleRoot -ChildPath $name | `
+         Join-Path -ChildPath $version | `
+         Join-Path -ChildPath ($name + '.psd1');
+
+    if (-not (Test-Path -Path $importModule)) {
+        Write-Information -MessageData ('Saving module {0}' -f $name) -InformationAction Continue;
+        Save-Module $name -Path $moduleRoot -Repository PSGallery -RequiredVersion $version;
+    }
+
+    Import-Module $importModule;
+}
+
+Import-ModuleLocally -Name PSScriptAnalyzer -Version 1.20.0;
+Import-ModuleLocally -Name PowerShell-Beautifier -Version 1.2.5;
+
+# Use Invoke-Formatter on all code
+# Using -Exclude breaks the -Filter functionality so a regex using Where-Object is used instead
+$psScripts = Get-ChildItem -Path $PSScriptRoot -Exclude 'psmodules' | `
+     Get-ChildItem -Recurse | `
+     Where-Object { $_.FullName -match '.*\.ps1$' }
+$formatted = $false;
+
+foreach ($script in $psScripts) {
+    $scriptPath = $script.FullName;
+    $initialHash = (Get-FileHash -Path $scriptPath).Hash;
+    $contents = Get-Content -Raw -Path $scriptPath;
+
+    # Use built-in PowerShell formatter
+    $contents = Invoke-Formatter -ScriptDefinition $contents;
+    Set-Content -Path $scriptPath -Value $contents.Trim();
+
+    # Use the Powershell beautifier
+    # It can't take a string input so have to use the file path
+    Edit-DTWBeautifyScript -SourcePath $scriptPath -IndentType FourSpaces;
+    $finalHash = (Get-FileHash -Path $scriptPath).Hash;
+
+    if ($initialHash -ne $finalHash) {
+        Write-Information -MessageData ('Formatted {0}' -f $scriptPath) -InformationAction Continue;
+        $formatted = $true;
+    }
+    else {
+        Write-Information -MessageData ('No changes to {0}' -f $scriptPath) -InformationAction Continue;
+    }
+}
+
+if ($formatted -and $exitCodeOnFormat) {
+    exit -1;
+}