Add comprehensive test suite, fix minor issues, rename function and file names to match approved verbs (#708)

Scripts/FileIO/Import-AppPresetsFromJson.ps1

@@ -0,0 +1,24 @@
+<#
+    .SYNOPSIS
+        Returns preset names and application IDs from Apps.json, or an empty array when unavailable.
+#>
+function Import-AppPresetsFromJson {
+    try {
+        $jsonContent = Get-Content -Path $script:AppsListFilePath -Raw | ConvertFrom-Json
+    }
+    catch {
+        Write-Warning "Failed to read Apps.json: $_"
+        return @()
+    }
+
+    if (-not $jsonContent.Presets) {
+        return @()
+    }
+
+    return @($jsonContent.Presets | ForEach-Object {
+        [PSCustomObject]@{
+            Name   = $_.Name
+            AppIds = @($_.AppIds)
+        }
+    })
+}